My Antique Mirror Is A Portal To Another World - Chapter 2: A Miracle

A part-time job contract. He became the cold CEO’s imitation boyfriend. He merely wanted to earn a few small bucks and live a comfortable life, but a pity, he was in constant turmoil since then. Well, life had something else for him despite his wishes.“That… beauty, will there be an increase in wages for conversion from ‘boyfriend’ to ‘husband’?”

- Description from Novelupdates

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.

A slime randomly falls into existence. Sapient and born with the ability to recreate parts of the things it preys upon, the highly confused drop of primordial soup decides that the only real thing it can do is become the being at the top of the food chain. A task of longevity in the leaves of the Omniverse.

The first time they met they had battled fiercely, just for a mere bunch of herbs. She needed it to save people, and he wanted to use it to save his own life.