OVA 3

The Ninja Who is Too Complicated (こじれすぎる忍者, Kojire-sugiru Ninja) is the fourth OVA of the One-Punch Man anime series.

Summary
After losing against Saitama, Sonic is struggling to cope and cannot fight properly after his defeat, even having repeating nightmares and flashback of the incident. He began training in a forest with a Matagi hunter who is looking to kill a bear that scarred him. After receiving some advice from the hunter, Sonic contemplates about it, but was disturbed by some noise. He arrives and saves a baby boar from a snake that quickly bonds with him. Naming the boar Ino, Sonic continues training, gradually regains his confidence and overcoming his fears.

He decided to leave and as he saying farewell the hunter corrects him and introduces himself by his real name Frank, which surprises Sonic. After leaving, the bear who scarred Frank appears and overpowered him and knocking him out, Saitama shows up searching for food. After eyeing Ino, the boar ran off, leaving Saitama taking the bear. At his apartment Saitama and Genos are eating hot pot with bear meat while Sonic silently watches over the city, ready for his next battle with Saitama. After Frank wakes up, he and Ino look with amazement at the forest cleared with a single punch.

Characters in order of appearance

 * Speed-o'-Sound Sonic
 * Frank
 * Ino
 * Saitama
 * Genos