Responses

Well japanese culture is very centered around living a long healthy life, one of the reasons they have good posture and stretch so much and stuff. Laying on your back is technically the healthiest way to sleep (other positions cause joint pain and tight muscles) so if this goes along with their pattern of ingraining healthy living since birth, it doesn't surprise me that many japanese sleep in this position
I don’t know why I’m thinking about that but in most mangas, characters are usually sleeping on their back. I mean I know it usually helps the scenario, but I always felt weird sleeping in this position, somehow I feel very vulnerable so I sleep in a fetal position... I’m curious: are there a lot of people who sleep on their back ?
Anyway why am I talking about that here, sorry .. ._.
Anyways, it was extremely cute. Kotarou was the definition of cuteness ╥﹏╥