Kombu Infinity is a villain from One Punch Man. He is a humanoid monster with a pitch black body with no distinguishable features other than it's large eyes and it's prehensile kombu hair, which is a strong as steel and he can stretch to attack.
Kombu Infinity arrive on the restricted area of Z-City after hearing rumors of powerful monsters living in the place. While he didn't find any monster, he is confronted by two A-Class heroes, Golden Ball and Spring Mustache, who were sent by the Hero Association to investigate the same rumors. Golden Ball attacks him by shooting one of his special golden balls, which Kombu easily deflects. He grabs Golden Ball's leg and drags him through a water drain then smashes him against a wall, knocking him unconscious. He then attacks Spring Mustache, who defends himself with his rapier but realizes he is outmatched, so he talks with the monster while calling for reinforcements.
After knocking Spring Mustache, Kombu decides to go after a populated area, but then crosses path with Saitama, who was returning from the market. Realizing the restricted area was not unpopulated, he decides to attack Saitama. The next scene then shows Saitama boiling some kombu, which he tells Genos he bought for a cheap price. When the other heroes arrive at the place, they just find an enormous crater over the buildings, so they assume another monster defeated Kombu Infinity.
The webcomic features an extra panel showing a crying Kombu Infinity with all of his hair stripped, implying that Saitama let him live.