Flowers Bloom from Battlefield - Chapter 401: Failed Plan

Kuramoto Daisuke, a freshman in High School was suddenly exposed to someone vanishing in front of him. Turns out he was admitted to a Special Class full of Isekai Heroes that were regularly summoned to Otherworlds since the start of their Middle School. He was told that he was to become their Support to prevent each of the Heroes' fate of dying in the world they were summoned into. Though mediocre, he realized that his ability has a great potential but it needs a lot of hard work on his part.

Unconvinced of being just the Support Character, he vowed to excavate his mediocre ability, all the while supporting the Heroes using it.

And maybe more.

What are you going to do when you pass through another world?

Yalin(MC): Perhaps, many of those seniors who passed through another world would like to use violence to solve their problems, but I like to control the fate of a country with economics and races with faith, I use benefits to instigate others so that I profit, and even making them take risk for me without them even knowing. In each country the highest is the king and behind the king is a string that is attach to my hand, for I am their puppeteer.

Yalin(MC): Certainly the credit does not only belong to me, I must give my thanks to the great knights and their leader Zero(Code Geass). The supreme master of blood, the moon princess(Tsukihime), the black and white princess, and also my ‘good friend’ called by his title the ‘God’s left eye’, president of the neutral autonomous city. Finally I must give thanks to my loyal and competent subordinates!

- Description from Novelupdates

Diablo Volfir, a mighty magician, was sealed for aeons due to the schemes of the 12 Gods, but 66666 years have passed since then, and he descends to earth once again!

The young lord of a small and weak country saves a dragon beside the sea one day.