|Relatives, etc.||Yuko Tachikawa (Sister)|
|Occupation||Police Sketch Artist|
|Anime debut||Episode 9|
|Manga debut||Chapter 20|
|English Voice||Christopher Patton|
Haruki Tachikawa is Yuko's older brother, who works with the police as a sketch artist.
Haruki is a man of average height and weight. He has brown hair and eyes and wears glasses. He is usually seen wearing a loose green jacket over an off-white long-sleeved shirt and dark blue sweat pants. When he's on the job, he wears suits.
Haruki seems to be a laidback person who cares for his younger sister. He told his sister classified information about parasites in order to keep her aware and protected.
He is later seen asleep on a couch when his sister comes home, waking him up. He notices his sister looking at the sketch of the parasite he made earlier and quickly takes it away from her. After Yuko begins asking questions, he admits to the existence of the monsters in order to protect her. He reassured her that they are far and few between and that the likelihood of her encountering one is slim.
In the manga he also mentioned wanting to capture a parasite alive, accidentally spurring Yuko to try to talk to Hideo Shimada.