https://www.dlsite.com/maniax/work/=/product_id/RJ265307.html

I remember this was a game. The mom gets isekai'd into another world with fantasy and magic as a dark elf. She fights like crazy to make it back to her son in their original modern day world. She didn't pursue any romantic relationships in that world because she wanted to get back to her son. There was some magical (dark elf marking?) reason I can't remember that made her see her son as a romantic interest after she got back. Naturally, since his mom is a super hot dark elf now, he enters into a more than mother son relationship with his mom.

Other part to this:

https://e-hentai.org/g/2266135/8f19333aeb/

Base +8, edson +14, zzzbbbzzz2003 +6