The Attack Begins is the 32nd chapter Ajin: Demi-Human, created by Gamon Sakurai.
Four hours before the fire in the security room Okuyama arrives after being employed, thanks to the help of one of the employees. After doing some work he uses a cigarette lighter he starts a small fire. Once the carbon dioxide was released Okuyama used his IBM to trap everyone inside the security server room. After being revived Okuyama proceeds to hack into forge security.
Once Tanaka learned of Okuyama's success, Tanaka, Takahashi and Gen stormed the forge security building. With Okuyama's help they get through the lobby and has the security shutters close behind them. The security teams are notified of Tanaka's arrival.
Two guards came to check on the security sever room at Okuyama's location. Using some electrical cables Okuyama killed the two guards and notified the other guards that the security server room has been infected with a virus.