Mosquito Girl attacks the city with her swarms which suck the blood out of everyone alive. An android named Genos tries to stop her but is having a difficult time. After dealing with a single pesky mosquito, Saitama sees Genos and Mosquito Girl fighting, and defeats Mosquito Girl. Despite Genos's extremely boring explanation of his past, Saitama agrees to make Genos his apprentice. Some monsters from a group called the House of Evolution try to capture Saitama, but fail. Saitama questions Armored Gorilla about what's going on.