MOCHIIII! I FUCKING LOVE YOU. And pfft the last part of the author's notes.
The lack of distinction between sex and gender in the Japanese language explains a lot actually. I remember learning about how there is a chicken-egg situation in linguistics. There are two theories. Either language dictates our perception of reality or reality dictates language. There is actually more evidence that it is the former. For example, if you ask someone whose only language does not differentiate between Red and Orange, or Blue and Green like in old Japanese, they literally can't tell the difference between the two colors. They are both red. I guess this is why for some people, the differences between sex, sexual orientation, and gender are crystal clear, and it seems completely crazy that people can't tell the difference, while for others think we are the crazy ones for seeing a difference