Kai is a new investigator for Kanto region's narcotic bureau. When conflicted with anything that involves pain or extreme emotional hurt to him, Kai might switch to a violent alter ego who has no problem in harming others, though Kai himself is gentle and reluctant to do anything dangerous or hurtful to others. 

At first glance, Kai seems like a typical, happy young man, but when in danger his personality becomes violent and unstoppable. As Hal struggles to keep Kai in check, clues about Kai's past begin to surface, and he begins to wonder whether his violent mood swings may have something to do with the mysterious events that occurred sixteen years prior. 

Two newbies at the Narcotic Control Department in Japan, Haru and Kai, struggle against: drug dealers, gangs, murderers, psychopaths, mysterious organizations, and mad people in general. The gentle and caring one of the group, Kai, who has problems of his own, has the tendency of turning into a lethal killing machine in certain scenarios. The way he acts changes like that of a "switch". As the two do their job, answers of what is behind Kai's strange behavior and who exactly he is, is revealed.
 
(Source: Anime News Network)

__Height:__ 173 cm
__Skills & Abilities:__ Kendo

[Profile (Pony Canyon)](https://www.ponycanyon.co.jp/artist/31356600) | [Twitter](https://twitter.com/black_fukuyama)

Fukuyama released his debut music album "Romantic World 31" on his birthday (November 26) in 2009, his second album "Love Letters 2: Paris Romantic" on July 21, 2010, his third album "Fukuyama Jun, Ai wo Utau!" on May 25, 2011, and his fourth album "Love Letter 3 ~Matsuri no Kuni de~" on May 22, 2013. He also appeared in a 2009 romantic comedy movie Fujoshi Kanojo in a cameo role.

**Non-anime roles:**
- [Joker](https://anilist.co/character/121590/Ren-Amamiya) - Persona 5 (VG)
- Renya Goutou - 13 Sentinels: Aegis Rim (VG)
- [Camu](https://anilist.co/character/278324/Camu) - Punishing: Gray Raven (VG)
- [Kamui](https://anilist.co/character/259960) - Punishing: Gray Raven (VG)
- Vyn Richter - Tears of Themis (VG)
- Martin - Rune Factory 5 (VG)
- Hugo - Zenless Zone Zero (VG)
- Logos - Arknights (VG)
- René Kincaid - The Legend of Heroes Series (VG)

Kai Eto may look like a squeaky clean kid, but the Greater Kanto Narcotics Control Division's new investigator hides a violent alter ego and a dangerous past. With his stoic partner Hal Kurabayashi, Kai is assigned to track down and stop the distribution of Dragon Speed, a dangerous new drug. But Ryugen, the syndicate trafficking the drug, is almost impossible to infiltrate. Add street violence and a jurisdiction war with the Meguro Police, and poor Kai is in for some very long days at the office.
 
(Source: Viz Media)
 
Included one-shots: 
Volume 2: Bonus Chapter 
Volume 6: Early Days; Bonus Chapter 
Volume 11: Bonus Chapter

Kai Etou