But based on this page http://www.mangago.zone/read-manga/usagi_no_mori/mi/0ad66d541cb0cedd57d538713c5ac0bb_chapter-1/6/
And the ensuing kiss on the lips, I think we are led to believe that the kid is sexually abused by his mum. I only noticed on the second reading, but it would explain quite a lot of things.
http://www.mangago.zone/read-manga/sono_kao_mitara_gaman_wa_dekinai/uu/sono_kao_mitara_gaman_wa_dekinai-chapter-2/9/
Unfortunately it's either sweat or poop, seme-kun.
I would not kiss that mouth. http://www.mangago.zone/read-manga/double_section/uu/ibx_chapter-6.5/pg-7/











I think Haruomi knew all along.