Gensei Kihara

Gensei Kihara (木原幻生, Kihara Gensei) is an enigmatic character appearing in Toaru Kagaku no Railgun, a side story of Toaru Majutsu no Index. A member of the Kihara family, he is a man obsessed with Level 6, and has made several attempts to achieve it.

He is a man of advanced age. His height is quite average, though he seems to have a hunch. His most notable feature is that he often has his eyes closed, only rarely opening it when he is excited, as well as a birthmark that can be found on his right temple. Gensei is currently the oldest Kihara introduced in the series.

As the creator of the Ability Body Crystal, his actions would influence the beginning of Toaru Kagaku no Railgun, and several characters in the later part of Toaru Majutsu no Index. For those reasons, he can be arguably considered the main antagonist of the Railgun side story. He is also the darkest Acadamy City character.

Personality
Typical of a Kihara, Gensei is a sinister figure despite his usually smiling expression; he has no qualms in killing people for the success of his research (even himself, as it was revealed during his second attempt to Level up a Level 5 Esper), which brings him at odds with Heaven Canceller, whose belief in the Hippocratic Oath clashes with Gensei eagerness to push the boundaries of science. He also admits that his eagerness has resulted in not seeing anything around him when something unexpected happens, and admits that this has caused accidents that have nearly killed him several times.

Perhaps because of this, and the fact that he fits the description the most that he is referred to as a "mad scientist".

An old man with an analytical mind, in the long time he has spent in the Dark Side of Academy City, he has become sensitive to people plotting something. He can see through people's deceptions through their mannerisms, for example Misaki still having "a glint of hope" in her eye, as such he was wary of her leading him to a trap.

Trivia

 * His name (幻生) literally means "Illusory Life", and maybe a reference not appearing at all in the series in the current year of the timeline. Using other characters (原生), it can be translated as "Primitive" or "Primeval", referring to his age. Furthermore, his name is used interchangeably with "Tensei", meaning Reincarnation.
 * Due to his evilness, Gensei acts like a Science Side version to Terra of the Left based on how immoral the two of them are, their willingness to sacrifice innocent people for their causes, and their disrepsect for human life which even their partners objected to.