Ren, the isekai'ed man into a cute (and extremely well-endowed) girl from the manga I Don't Really Get it, but it Looks like I Was Reincarnated in an Another World! Man, those titles though. Japanese title is Yoku Wakaranai Keredo Isekai ni Tensei Shiteita You Desu. I goofed on the tag a little but it's fine, not retraining it for two letters missing. :)

She spends a lot of time in the manga on her "routine", which is code for "locks herself in her room and plays with herself for days", it's pretty silly.

Trained on PonyXL, for SFW/NSFW.