I Only Summon Boss Monster

Kheatix Ago never expected death to become the start of a legendary journey.

Reincarnated as a baby in a vast isekai world ruled by swords, magic, kingdoms, and monsters, Kheatix is born into an ordinary commoner family with no noble blood, no wealth, and no special talent. In a world where power determines status, only the strong are respected.

But Kheatix is neither strong nor gifted.

Quiet, timid, and physically weak, he grows up being mocked by villagers and looked down on as a coward who could never achieve anything. Even after awakening his class, Summoner, people laugh at him-calling it a weak class meant for those who hide behind creatures instead of fighting.
Until everything changes.

During a dangerous encounter with a powerful monster, Kheatix awakens a unique ability no summoner has ever possessed:
Boss Summon.

Unlike ordinary summoners who call weak beasts or spirits, Kheatix can summon only Boss Monsters-legendary creatures feared across dungeons, battlefields, and ancient myths.
But there is one rule.

A Boss Monster can only be summoned after it has been defeated-whether Kheatix defeats it himself, or someone else brings it down. Once recorded by his power, that Boss becomes part of his summoning arsenal forever.
From giant dungeon tyrants, ancient dragons, cursed kings, demon generals, and forgotten world beasts, Kheatix begins building an army of monsters no kingdom could ever imagine controlling.

What began as the journey of a weak and ridiculed boy slowly turns into the rise of a legendary summoner feared by heroes, nobles, and even demon lords.
Because in a world where everyone seeks strength...
Kheatix Ago doesn't tame monsters. He commands the Bosses.