TouKasa

TouKasa is the slash ship between Touya Aoyagi and Tsukasa Tenma from the Project SEKAI fandom.

Canon
Touya and Tsukasa are both students of Kamiyama High school, with Tsukasa being a 2nd-year student and Touya his junior by one year. The two are also childhood friends who knew each other through their parents' connection. Touya is seen to regard Tsukasa with respect and admiration, and this is expanded upon in the KAMIKOU FESTIVAL! Event.

The Tenma Household's Hinamatsuri Event focuses on Tsukasa and Saki, but Touya (along with Honami Mochizuki) also play a large role in the story to help the siblings make up after their fight.

Tsukasa often points out that Touya smiles a lot more often now compared to the past, and accredits this to Akito and Vivid BAD SQUAD.

Fanon
The fandom often groups Touya together with Tsukasa and Saki Tenma as part of the Tenma Family. This is also because of their relationship being described to be like that of siblings in canon.

Although some people prefer to see their relationship as platonic, others also like to see their relationship in a romantic light. The contrast between Touya's usually calm and poker-faced demeanor with his sparkly-eyed expression when praising Tsukasa is one of the ship's appealing points.

Quotes
"If not for Tsukasa-senpai’s words back then, I wouldn't be the person I am today. That’s why he's the person who changed me... my savior."

- Touya, from KAMIKOU FESTIVAL! Chapter 4

"In the past, I used to try so hard to make you laugh, but it seems like I don't need to do that now. You're like a little brother to me, and following after Saki, you're my #2 Fan. I should thank Akito for making you smile."

- Tsukasa, from A Bond Between Siblings Card Story 1

"I also have brothers, but we're apart in age. And they studied abroad while I was still young, so I don't have a lot of memories of us bonding as siblings. Besides, back then, I wasn't allowed to play with friends. It was very painful for me as I practiced the piano and violin. But ever since that day, my parents would leave me at your house and we would play together, and you'd show me plays. That had become my emotional support."

- Touya, from A Bond Between Siblings Card Story 1

"...Come to think of it, Touya dragged me along to buy some stuff with him last year around this time too. So that was for Tsukasa-senpai's birthday, huh."

- Akito, from his birthday line for Tsukasa (May 25, 2021)

Fandom
FAN FICTION

PIXIV

Trivia

 * In the game's default party names for Cheerful Carnival events, Touya and Tsukasa in the same team together would have the optional party name of "Respect and Deep Affection".
 * In the 24th Project Sekai Summer Vacation Radio broadcast for Wonderlands x Showtime, when asked which character they would want as a brother, Tsukasa's Voice Actor (Daisuke Hirose) answers Touya.