Rise of the Strongest War God - Chapter 7: First kill

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.

There’s a legendary Bishoujo Game that has become popular among Japanese gentlemen.

Ukei Kaito fought a desperate struggle in order to fulfill his role as a summoned hero. He defeated the Demon Lord and saved the very world, only to meet an end filled but with betrayal. The companions that he’d trusted throughout his journey betrayed him and killed him by sticking a blade through his chest.

With his engagement at hand, the most terrifying and legendary person of the legal world, Fu Huai’an, returns with a son.

Before the engagement…

He asks, “Since you love Wen Moshen, why are you in my bed?”
She says, “Because I cannot watch idly as Wen Moshen’s woman enters an engagement with you.”

With a cigarette in Fu Huai’an’s mouth, he crosses his legs. Across the light cloud of smoke, he squints his eyes—watching as Lin Nuan’s slim arms wrap around his neck; he feels stirred.

So a person can love another so passionately.

“You call what you did a kiss?”
“…”
“What a pure lady!”

Fu Huai’an spews out a cloud of smoke and snuffs out the cigarette. With a mellow voice, he says, “Let me teach you what kissing is!”

But, what he teaches Lin Nuan doesn’t seem to be only a kiss…

- Description from Novelupdates