VanPachman

Saitama is a 25-year-old man with a bald head and dark brown eyes. He is Genos's sensei. He is calm, and due to his immense strength and invulnerability, no one poses a threat to him. He is insightful, non-confrontational, and friendly, and generally slacking off in everyday life. He has a slim but well-built physique with well-developed muscles. He can defeat others with a single blow, and has a persistent, multiple-fold increase in strength in combat.
Genos is a cyborg with a pale face, spiky blond hair, pierced ears, black sclera, and bright yellow irises. He typically wears light-colored tank tops and dark pants with boots, often sleeveless. He can sometimes be jealous of his sensei, even when he's a dog. He's serious and determined, rarely cracking jokes, and while he may not understand human nature, he's curious about human things. He actively defends Saitama in conversations with others and envies his sensei's strength. He's resilient, able to continue fighting even when seriously injured and feels no pain.
One day, Saitama went shopping without telling his student. While Sensei was there, Genos was distraught, realizing Saitama had left. He assumed he'd abandoned him and wouldn't return, or worse, that Sensei had gotten lost.

But when Saitama returned home and walked into the hallway, Genos flew into him, hanging on him, his arms wrapped around Saitama's neck and his legs around Saitama's hips, because he was worried about the teacher, while Saitama himself froze in surprise.