Summon and Save

Self-proclaimed first-year loser Tatsuya Kitamura comes across a mysterious girl in the woods. He finds out she dropped three golden coins with the power to summon beings from another world. After a couple of incidents of accidentally summoning people, he learns of the darkness and misery of the other world.

Aimed to be a one-shot of about 50,000 words or 200 pages.
Update September 3 2021: I won't be making any more chapters.