"Business Activity" (営業活動, Eigyō Katsudō) is the 18th chapter of the One-Punch Man manga series.
Five days after their debut as pro heroes, Genos asks Saitama if he can live with him. Saitama protests until Genos offers to pay rent and throws a rather large stack of bills onto the table. Afterwords, Saitama is relaxing and Genos is taking notes on everything Saitama does in hopes to learn the secret of his power. Saitama starts to think of ways to get Genos out, but is interrupted by Genos who tells him that C-Class heroes get expelled from the organization if they have been inactive for more than a week. Saitama had not known this and rushes out of the apartment to find a crime to solve. Saitama rushes all through out town, but doesn't find anything and gives up. The next day he does the same thing and is freaking out about being expelled when he catches a kunai that was thrown at him by Sonic, who's name he'd forgotten.
- A murder of crows flew and began eating Beast King remains. They began mutating and gained a small human-like body and the ability of using eating utensils.