Naruto: Otsutsuki Yuexin

An ordinary high school student transmigrates into the Ōtsutsuki Clan in the Naruto world. But unlike his predecessors, he doesn't become a member of the main family. Instead, he is a servant, just like Ōtsutsuki Kaguya.

At last, when the clan holds a selection to choose those who will go to the Shinobi World to capture Ōtsutsuki Kaguya, he volunteers and is luckily selected. He then uses his foreknowledge to befriend everyone in the Shinobi World, joining them to resist the invading Ōtsutsuki Clan.