Until yesterday, there was a significant difference in the flow of energy from the center of the head to the left and right. Although the energy was flowing to the right ear to some extent, it was not flowing to the left ear. Although the flow to the left ear had been improving recently, it was still not flowing.
This morning, a tingling sensation like static electricity began to build up from the lower part of the left eye, and then energy gradually flowed from the eye to the upper part of the left ear. Because the flow felt good, I continued meditating, and as a result, the energy flow in the upper part of the ear became almost the same on both sides. However, it still feels like the right side is slightly better, but this difference seems like it might be within the margin of error.
I could have stopped meditating here, but I still had time, so I continued meditating. I felt that the part connecting from the upper part of the ear to the back of the head was weak in terms of energy, so I continued meditating to connect it to the Sahasrara chakra.
Then, it seems that the activation gradually progresses from the ears towards the upper back of the head, and the upper right and upper left areas of the back of the head, connected to the upper parts of the left and right ears respectively, become activated, and the energy of the Sahasrara chakra seems to stabilize in a triangular or circular shape.
This makes it easier for energy to connect from the center of the head to the left and right ears, which corresponds to Ida (left) and Pingala (right) in yoga. This activates the energy on the left and right sides of the body. Furthermore, by connecting to the Sahasrara chakra through the area near the ears, the Sahasrara chakra itself seems to be activated.
Previously, the conditions for the activation of the Sahasrara chakra were not so clear, and there were times when it felt open and times when it didn't. However, it is likely that being open in only one point is unstable, and the route that rises from the center of the head or near the eyebrows is probably the basic one. Even with that alone, the Sahasrara chakra opens to some extent, but by adding the connection from the ears to the Sahasrara chakra through the left and right sides of the back of the head, it seems that the Sahasrara chakra becomes more stable by being activated in a circular shape with three points as support.
This is still a hypothesis, but I also feel that it is likely to be true. I will continue to verify this and check for reproducibility.
...This is what happened this morning.
On the same day, when I visited Jisho-in at Naritasan Shinshoin in Chiba, I enjoyed the sightseeing comfortably until a certain point. However, when I entered the Heiwadai Tower, which is located in the innermost part, and was surrounded by the giant statue of Fudo Myoo and Tibetan-style colorful mandalas, the Sahasrara chakra suddenly tingled, and I entered a meditative state. I stood still for a while, observing and focusing on the Sahasrara chakra, and first, as I experienced this morning, the energy in both ears, the upper back areas, and the entire head increased.
Then, as I continued in that meditative state, another state progressed, and the upper front areas of both ears (on the left and right sides almost simultaneously) began to activate.
With this, a total of 5 points, the upper front area, the upper front and back areas of both ears, became focus points, and the Sahasrara chakra became activated in a relatively circular shape in the head.
I observed that the upper front area of the right ear was less activated than the same area on the left, so I focused on activating that area, and mostly balanced the left and right sides. It is easier to do this in this location. At home, it often takes about an hour or two for something that happens quickly here.
And then, I stopped for a while in a more meditative state, and after calming down somewhat, I left that place. I still feel that the summit is a bit difficult, but for now, I think it's sufficient for today.
As an addition,
I received some inspiration at that place, and I thought (even now) that Japanese Buddhism should have visited the Himalayan sages and learned from them (perhaps a few centuries ago). If it had been the Age of Exploration, there would have been plenty of opportunities to go to Rishikesh or Gangotri in the Himalayas and learn from the sages. Even during the Sengoku period, if some enlightened people had sought enlightenment in the Himalayas, and if their teachings had been reintroduced (to Japan), Buddhism might not have declined so much and become what it is now, a "funeral Buddhism." I felt a sense of regret and hope, as if saying that if the Buddhist temples had not been spending money on luxuries during the Sengoku period, even a portion of that money could have been used to send someone aware to study in the Himalayas. I feel that it's too late to talk about the Sengoku period now... I wonder if there is someone there, a soul filled with regret.
Here's a summary of the changes:
1. Be aware of the left and right sides from the center of the head. Activation of the left and right sides of the body, such as the cheeks, chest, and shoulders (Ida and Pingala).
This is a basic practice that has been ongoing recently, rather than just today. This morning, I started with this basic practice.
The awareness is simply focused on the left and right sides of the head, and (relatively automatically), energy flows through the left and right cheeks, to the left and right sides of the chest, the left and right shoulders, the left and right arms, and the left and right legs, activating them. In yoga, the Ajna chakra, located between the eyebrows, is said to be where Ida, Pingala, and Sushumna intersect. In my case, the connection to Ida and Pingala seems to be weak, so simply being aware of it improves the flow of energy. I suspect that once the energy flows properly, it may no longer be necessary to consciously activate it, but I am not yet fully open, so I am consciously focusing on the left and right sides.
2. Route from the center of the head to the left and right ears.
Center of the head → Right ear: I have experienced this recently, and it is working to some extent now.
Center of the head → Left ear: This morning, I finally opened this channel (as described above).
3. From the ears, towards the upper back (on the left and right sides).
This morning, I opened this channel (as described above).
4. From the ears, towards the upper front (on the left and right sides).
On the same day, at noon, I opened this channel (as described above).
5. From the back of the head, upwards.
The next morning, I was meditating, focusing on the areas mentioned above, and I felt that energy was flowing directly from the back of my head to the crown of my head more strongly than before. However, it still feels like the connection is not complete. This may be a challenge for the future. It can be considered the sixth focus point, but it feels thicker than the other points, so it may be the sixth point, or it may be a point slightly inside the other five points.
It is similar to a pentagram or a hexagon in terms of geometry, so I tried drawing a diagram. I am not feeling these lines and shapes in terms of energy, but I just tried drawing it. The initial feeling is more like a thick pillar rising from the intersection of the points of a pentagram, but when I draw it, the pentagram doesn't quite reach the intersection, so the hexagon feels more appropriate. In terms of feeling, there is a pillar extending from the back of the head inside the pentagram, but it doesn't translate into a diagram. It may be that a pentagram is actually the correct answer, and my feeling is correct, even though it cannot be written on a flat diagram. In the astral world, the constraints of the material world are lifted, so such things may be possible. It might be possible in a three-dimensional pentagram-like shape, but what do you think?
It seems like a temple is being formed in my head.
For now, I will reserve my judgment until today.

5. The inside of the occiput.
It has started to make a "mishimishi" or "baki" sound in the slightly inner part of the upper occiput, or slightly behind the center of the head.
(This is the main issue, but unexpectedly, it makes a "baki" sound in various places, such as the upper left side of the head.)
6. The inner part of the top of the head and the epidermis of the crown.
A few days later, along with a "pirit" sensation like electricity, I felt a "bih" sensation throughout the scalp of the crown, and at the same time, I felt a sensation like "a wound touching saltwater" for a moment, and there was a slight pain in the wound, but it lasted only a moment and quickly subsided. Since then, the aura has become easier to reach the entire Sahasrara, and the Sahasrara has become easier to activate, but it doesn't feel like the energy channels have been properly opened yet.
7. From both cheeks to both ears, and towards the crown.
The aura is somewhat flowing from the upper cheeks, through both ears, and towards the crown, but it loosens repeatedly because the upper half of the head is still stiff. The area slightly inside both ears is also stiff, and the upper cheeks are stiff, and there are many stiff areas towards the crown.
8. The stiffness of the area between the eyebrows, the forehead, and the depths of both eyes.
About a week later (11/16).
This area has loosened somewhat, but it is still very stiff, so I am carefully loosening it repeatedly. Even so, it is still stiff. Occasionally, there is a strange sensation in the area between the eyebrows, like "heat" but not quite, a "buzzing" sensation that is there or not, a feeling like wind, or something like that, a strange feeling that I have never felt anywhere else, but even so, the stiffness in the area between the eyebrows still persists. The forehead is also stiff, and I am loosening it repeatedly. The depths of both eyes are also stiff.
In this way, I am repeatedly loosening various parts of the upper half of the head, but at least, it seems that the area below the boundary between both ears and both cheeks has loosened to some extent. The middle part is not completely loosened yet, but the boundary is roughly around there.
Regarding the lower half of the head, it has already loosened to some extent, and the "baki baki" or "mishimishi" sounds have almost disappeared. However, previously, it was making the same "mishimishi" and "baki" sounds as the upper half of the head, so I have a feeling that the upper half of the head will also loosen suddenly and in parts, just like the lower half.
Although there is still overall stiffness, I feel that it is gradually and steadily loosening with persistent meditation.
9. Auras pass through the left and right back of the occiput.
The next morning (11/17), while meditating, I felt a swelling sensation in the left and right back of the occiput, areas where auras usually don't reach. It felt like energy pathways were forming from the lower part of the occiput, passing through the left and right sides, and gradually moving upwards. Although the entire occiput is not yet fully activated, at least the lower half of the occiput seems to have been activated to some extent.
10. Relaxing the upper half of the head.
Recently, and especially today (11/17), my head feels like "cartilage." This sensation, combined with muscle tension, creates a feeling of constraint within the head. I meditate to further relax it. During meditation, these "cartilage-like" areas stretch, and when they stretch to a certain point, the constraint (slightly, in that specific area) is released, literally loosening it a little. I repeat this process.
In some areas, the cartilage feels like "muscle," while in other areas, it feels like a "covering" with different degrees of looseness on the inside and outside. The inside may be loose, but a stiff covering (made of cartilage) may be present on the outside. In some cases, there are "cracks" (like fissures) between the cartilage, allowing for some movement, but in other cases, there is no movement at all. I meditate and repeatedly stretch and contract these areas from the inside, using breathing to create movement and gradually release the blockages.
I have done similar things in the lower half of the head, the sides of the head, and even the occiput, so the basic process is the same. Currently, the main focus is on the upper half of the head, the central area, and the frontal lobe and forehead, which are more forward areas.
11. The hair on the top of the head becomes statically charged.
During the meditation that night (11/17), in addition to loosening, the hair on the top of my head became statically charged over a relatively wide area, causing a tingling sensation. The static electricity covered almost the entire head, a size that would make the hair stand up like a Super Saiyan. However, when I touched it or looked in the mirror, there were no physical changes. So, it seems to be just a sensation. When I touched the ends of my hair, they felt relatively normal and showed no particular changes. Therefore, I felt like the static electricity was all the way to the tips of my hair, but since it's related to the head, it might be an illusion, and it might actually be about the area closer to the scalp.