Sorry, idk, I'm just ff
sorry fallowing
ff
dont know about the cute things, but the rest is similar
http://www.mangago.zone/read-manga/ore_no_tenshi_wa_mayonaka_akuma/
ff
I think it's something by Mishima Kazuhiko, maybe part of a collection, but couldn't tell you specifically which one. I recall that once the kid starts aging he does it very rapidly.
Following~~~
Does anyone know that one yaoi where a preschool teacher or something is like really harsh but actually loves cute things but then his new student who he finds adorable stopped growing when he was young and only when the student is asleep does the real on come out anyone know??? ╮(￣▽￣)╭