Responses
Ok I missed that too until now that I read your post.
Yeah they place that part in the story subtly, it doesn't justify everything but it shows how the door to chaos was opened. Sucks when you think of someone as a friend but they only have ill intentions towards you. Reo truly trusted Kenta.
When I first read this a little while back I didn't catch the part that Kenta drugged Reo and that's what made him beg Uncle to hold him the first time. http://www.mangago.zone/read-manga/katsubou_no_manazashi/tr/75675/page/77/
Everything got all twisted after that,