KuboKai

KuboKai is the slash ship between Kaidou Shun and Kuboyasu Aren from the The Disastrous Life of Saiki K. fandom.

Canon
At first, Kaidou didn't have too much of an opinion on Kuboyasu, until he saw him interacting with a group of delinquents, therefore leading to the assumption that he was one. Kaidou, being terrified, decided to keep his distance from Aren. Despite this, Aren was unaware that Kaidou knew he was a delinquent and still attempted to befriend him. Kaidou just decided to get on Aren's side, as he was scared, and so that Aren couldn't attempt to beat him up.

However, Kaidou's initial negative impression of Aren was shattered after Aren rescued him and Saiki from a group of delinquents trying to steal their money. After that, Kaidou decided that Aren wasn't the guy he was in the past and the two soon formed a very close bond. It didn't take long before the two were on a first name basis - which implies a close bond with someone in Japan. Kaidou considers the two 'Sworn Friends'.

Throughout the series, the two have an extremely strong bond with Kaidou swearing to protect Aren from the Dark Reunion and Aren actually protecting Kaidou. It should be noted that Aren was one of the few people that Kaidou pursued to have a friendship with while the others just happened over time, and Kaidou was the first true friend that Aren made after deciding to stop being a delinquent.

Quotes
"Why is he looking at the bat like it's his former buddy?"

- Kaidou panicking as to why Aren does this.

"From an outsider's perspective, you two look like that too."

- Saiki pointing out that Kaidou and Aren look like a couple.

Fanon
KuboKai sailed as a result of Kaidou and Aren's close bond. The fact that Kaidou and Aren got along so quickly and that Kaidou managed to look past Aren's delinquent phase helped to make the ship popular. The two are so close that others even make jokes about how the two look like an old married couple and even Saiki sometimes acknowledges it.

The ship is relatively popular in the fandom, with KuboKai being the most written ship in Saiki K tag, before Saiai. There's quite a few scenes with the two that could be interpreted as romantic depending on the viewer's perception, although there's not enough solid evidence to entirely prove that they're both romantically interested in each other.

The ship sometimes falters in popularity to Kaidou's slightly more popular ship with Saiki, but due the fact that Saiki is implied to be not interested in romantic relationships, a rather large part of the fanbase prefers this ship over KaiSai. Another rival ship for Kubokai is Kaidou's ship with Chiyo, due Chiyo's confirmed (and quite obvious) crush on Kaidou, but some fans prefer to ship her with Aiura Mikoto in order to pair off with someone else. Nonetheless, KuboKai will remain very popular because of Kaidou and Aren's strong bond and hilarious friendships. Even if not a romantic ship, many fans can agree that their bond of friendship is beautiful, strong and definitely worth remembering.

It is the most written for both of them on AO3, as well as the second most written within the entire fandom.

Fandom
FAN FICTION

TUMBLR

Trivia

 * Aside from Aren's family, Kaidou is the only person who calls Aren by his first name, as well as vice versa.
 * Saiki himself said once that the pair looks like a couple from an outsider's perspective.
 * Due to physical attributes, the ship is comparable to the ship between Sakata Gintoki and Takasugi Shinsuke from the Gintama fandom.
 * The two are known for basically being mirrors of each other, in their reactions to situations and comments on things.