We said we were going to be a summoner, but what the hell is this Darkin Sword Demon?

[LOL elements + superpowers + all the way forward + invincible upgrade]
The void invades, strange beasts run rampant, and demons from outside the domain are watching covetously.
In order to withstand these multiple crises, humans are forced to open their genetic locks, giving everyone the opportunity to awaken their special powers at the age of 18.
Lu Chen traveled through time and space, and learned the summoning technique at the awakening ceremony in his senior year of high school, and obtained the S-level passive ability - Soul Contract!
Unlike other summoners who have weak bodies, Lu Chen can obtain all the abilities and attributes of his summoned creatures.
only...
The creature he summoned seems to be a little different!
Others are tree demons, undead, monsters, and goblins.
And what about Lu Chen?
A grumpy darkin dude with a giant sword!
A foul-mouthed Yordle riding a lizard!
The indomitable orphan wind swordsman!
The Ninja Lightning Squirrel who has lived for nearly ten thousand years!
Even the Star-Forging Dragon King who rubs planets with his hands and dominates the universe is Lu Chen's summon!
and many more,
Why is there a succubus here? ?
This book is also known as "Starting with a Darkin Greatsword, You Call This a Summoner?"