I can't find it in my lists - help me please, i've been looking for 3 days straight and can't figure out the name

story: high school guy (who was trained by his grandpa in some secret overkill martial arts with/without weapons) is summoned into some fantasy world. protagonist is pretty clever, good at analyzing situations, and a cold blooded killer (comes from his training) etc. Decides to kill the guards because the are emitting killing aura and gets the fuck out of the castle.

he hides downtown, buys some weapons and is looking for something?

he rescues two girls (slaves) who form a new contract with him

It's bloody good I really wish to find it - any help is appreciated

artwork: modern (i think the manga is not older than 2 or 3 years, could be really new) realistic artwork

further hints: i think the title is about 3 to 5 words long (i hope I've got that still right)
i read 5 chapter (1 to 4, 5 was missing, 6 was there)

To be an immaculate member of a flock of sheep, one must above all be a sheep.

Wortenia Senki

~4400 manga completed
~1700 ongoing...