Edit
Ero RPG from Satou (satohstc) featuring shotas and monster boys.
Japanese links:
- DLsite : http://www.dlsite.com/girls/work/=/product_id/RJ192037.html
- DiGiket : http://www.digiket.com/work/show/_data/ID=ITM0149654/
- BOOTH : https://satohkatoh.booth.pm/items/413177
English links:
Nobody here but us chickens!