Responses
He already knows. He was told of the possibility at the end of chapter three and got a paternity test:
http://www.mangago.zone/read-manga/haru_o_daite_ita_alive/mf/c004/66/
really can't wait until Iwaki finds out he had a son and katou knew about it didn't teell him. I feel so bad for shou to be treated like that and to be sexually abused by chibi just for a role.. still this manga is one of the best yaoi you can read!!