NOVEL NEXT Novel info
Touhou: A New Mage in Gensokyo
The MC got Isekaid in the world of Gensokyo and met Sanae, who helps him in this new World. The MC has potential to be a powerful mage but he knows nothing about magic.
I got the image from: https://danbooru.donmai.us/posts/4262455?q=kanpa_%28campagne_9%29+kochiya_sanae+ (I love campagne9)