- Name: Detective Akaiwa (赤岩刑事, Akaiwa-keiji?)
- Classification: Earthling
- Homeland: Daikanyama, Shibuya, Tokyo, Japan
- First Appearance: Monster Extermination Days
- Trademark Techniques: Kenka Sappō Gobugari Special (喧嘩殺法五分刈スペシャル)
- Theme Song: "Hitori" (ひとり) by Tetsuya Watari (manga only)
Chief Inspector of the Jōsai ("West of Tokyo Imperial Palace") District Police. He is a parody of Tetsuya Watari's cop character Raisuke Kuroiwa (黒岩頼介) from the TV series Daitokai (大都会). When there's trouble, he and his men the Akaiwa Corps (赤岩軍団 Akaiwa Gundan), will often show up with machine guns blazing and then leave without actually solving anything. In the manga he only appears in two stories, but in the anime he appears frequently and for legal reasons he is renamed "Gobugari (五分刈 "close haircut"), Police Inspector of the West Sumidagawa Station". He was referenced in Ultimate Muscle briefly as "Detective Tommy Gunn."