Eighteen's Bed - Chapter 13.3: Go Yohan, Go Yohan (3)

Based on the popular Vocaloid series, by HoneyWorks, called “Kokuhoku Yokou Renshuu (Confession Rehearsal)“:

Natsuki, a third-year at Sakuragaoka High School, who holds unrequited feelings for her childhood friend, Yuu, who’s in the Film Club. However, instead of being honest about her feelings, she makes him be her confession “rehearsal” partner. Unable to say her true feelings, things start to get complicated when Miou and Akari, who are also in the Art Club, get involved! Will she ever be able to confess for real!?

Humanity was on the brink of destruction. Muyoung, an assassin from the Forest of Death, fell to his knees. There were corpses all around him. For years, he had worked for the Forest of Death and had finally been able to eradicate them. Now, he, himself, was about to die. He closed his eyes as he felt his heart stop beating.

A long time ago, the decayed main god space collapsed and disintegrated, and the wreckage was scattered in parallel universes, giving birth to a new space…

Countless ‘story worlds’ under control have also fallen into the void, regained freedom, runaway out of control, elevated to reality, and turned into reality.

At the same time, these “worlds” are polluted and corroded by the void, giving birth to greater fear and filth…

…

The space of birth feeds on the world.

They compete with each other, their tentacles penetrate through dimensions, invade different time and space, search for the legacy of the main god, drive the apostles to be minions, greedily tearing, seizing, devouring, and reclaiming one world after another, so that they can return to greatness.

…

The innocent eating melon and white waves with the legacy of the Lord God accidentally got involved in the parallel universe “Paradise of Fire” during a cross-border call.

After forcibly binding the demi-human blood, he became an excellent tool man who can repeatedly die, starting the legendary ‘dimension invasion career’.

- Description from novelbuddy

When a fantasy kingdom needs heroes, they skip the high schoolers and summon hardened Delta Force operators.Lieutenant Cole Mercer and his team are no strangers to sacrifice. After all, what are four men compared to millions of lives saved from a nuclear disaster? But as they make their last stand against insurgents, they’re unexpectedly pulled into another world—one on the brink of a demonic incursion.Thrust into Tenria's realm of magic and steam engines, Cole discovers a power beyond anything he'd imagined: magic—a way to finally win without sacrifice, a power fantasy made real by ancient mana and perfected by modern science.But his new world might not be so different from the old one, and the stakes remain the same: there are people who depend on him more than ever; people he might not be able to save. Cole and his team are but men, facing unimaginable odds. Even so, they may yet prove history's truth: that, at their core, the greatest heroes are always just human.