Seikatsu Mahoutsukai no Gekokujou

I'm not "useless!" I'll prove it by conquering dungeons! Suddenly, magic and dungeons appear in modern Japan, and life has changed completely. I, Gurimu Sakaki, am born with a talent for life magic that cannot be used for exploring dungeons or defeating demons. I was born with a talent for life magic, but while exploring dungeons, I got my hands on a rare item, the "Sage System," which allows me to create new magic...? (Source: Kadokawa, translated)