Isekai manga where the protagonist is the extra of a friend group and gets "kidnapped"

Question

The main character gets summoned and is the extra of a group of four friends, I think.
They go get weapons, he can't pick them up, they go outside to train. There he gets kidnapped by a "monster" from underground, to wake up naked next to a computer that allows him to choose OP skills.

That's all I can remember from the first bit.
Later on, around mid story, he finds a slave in the snow and becomes her master. The slave summons a "goddess of the void" or something, and she kills the slaves' original owners.
He at this point has a stat board that says like 1.00e+40 or something like that, and he is pretty much a god.

Answer 1

This is Makikomarete Isekai Teni suru Yatsu wa, Taitei Cheat, also identified here and here.

One day 's lunch break, suddenly a male high school student Yuzo Ogata who has been transferred to another world of sword and magic together with four other friends. According to the Princess of Space-Time Magician, a foreign world who summoned them, they want them to beat the Demon Lord as Heroes to save this world. Suddenly I was surprised at four friends "Temple", but it was a relaxing expression ... ... where the princess told of a startling fact!" "―There should only be four braves though?" A man who was mistakenly summoned to a different world.

The synopsis covers the "extra" bit - five people were summoned, but there should only have been 4. The MC does not apparently have any special powers - for example, he's barely able to lift the weapons the others use with ease.

He gets attacked and kidnapped by a mud monster and suddenly finds himself in a temple with a regular desktop computer.

This awakens his godlike powers, which he uses to save a slave trader from bandits, and purchases a slave girl.

I didn't see any exponential notation in his stats while reading through this.

Found by searching mangaupdates for the tags Transported to Another World, Slave/s, and Overpowered Protagonist.