MyLittleBrother
It's will be super awkward if his little brother wake before him. Especially when she is playing with it.
Those tags are completely unnecessary if the s*x scenes aren't written. Just having in cest doesn't require those tags. Furthermore, this is the second time it's been hinted that his sister plays with his thing. The first time was in chapter 3 where she said it was cleaned and he said not to play with his body.
JustABoxWithAmmo:It is unknown whether this one would have such or not. However, the author would put in such tags a long ago. 18+, lemon, Dual cultivation or smut.