TsuKou

TsuKou is the slash ship between Yugi Tsukasa and Minamoto Kou from the Toilet-bound Hanako-kun fandom.

Mitsuba Arc
Tsukasa and Kou have their first encounter during Episode 8 of the Anime, and Chapter 19 of the Manga. Tsukasa appears in front of the door that he and his friend, Mitsuba were exiting from and says ominously, "Miiitsuuuba-kun."

Kou turns around, and assumes that Tsukasa is Hanako at first glance, but realizes that it isn't and internally questions who he is. A few moments later, after seeing what he had done, he goes in to punch him, but Tsukasa is stronger than him and slams him into a wall, making him bleed from the forehead. But Kou gets up again and grabs Tsukasa by the shoulder, asking him who he thinks he is. Tsukasa only responds with, "...wow."

Tsukasa explains to Kou that he is a supernatural, and that for the right price, he will grant the wish of anyone who summons him. And then he goes on to thank Kou for helping him draw out Mitsuba's real wish.

Hell of Mirrors Arc
The pair meet again during the Hell of Mirrors arc, after Yako leads Kou and Hanako to the 3rd Boundary. Kou blames Tsukasa for Mitsuba's disappearance, and Tsukasa seems pleased by it.

Fanon
There are few that actually ship this, but there are some out there. There is a semi-popular headcanon that Tsukasa did what he did to Mitsuba because he was jealous of him for having such a good relationship with Kou so quickly, but that is obviously just a headcanon.

People tend to stray away from this ship, as TsuKou can be seen as incredibly toxic considering the pain Tsukasa causes Kou, and the strong hatred Kou has for Tsukasa.

People tend to ship Mitsukou, Kounene or Hanakou for Kou, and TsukaNene and TsukaSaku for Tsukasa respectively.

Fandom
FAN FICTION

Trivia

 * Koutsu, one of the ship names for this pairing, is written on Kou's Traffic Safety Earring. "交通安全" (Koutsuu Anzen)