Yukise

Yukise is the slash between Yukiteru Amano and Aru Akise from the The Future Diary fandom.

Canon
Yuki first meets Akise when he is seen looking at him from across the street and smiles at him before disappearing when Yuno took Yukki's attention away from Akise. Yukki later learns that Akise is in his class, but skipped school that day to do detective work. When Yukki, Yuno, Mao, and Kosaka are surrounded by dogs who "killed Hinata", Akise comes out of the trees offering his help, assuring Yukki that he can be trusted. He comments on how he thinks Yukki's trembling is adorable, then saying they should go to the observatory, while Yuno is still suspicious of Akise, claiming he's the one controlling the dogs.

Akise helps everyone board up the windows and the dogs give up. Then, Mao unexpectedly put a knife to his throat and took away his diary, while Hinata appeared claiming she faked her death so she can kill Akise with her dogs because Akise was a diary holder. Akise suggested they play a game where he would toss a coin and Hinata had to guess which hand he caught it in, where if he wins, Yuki can be free and if Hinata wins, she gets to kill Akise and keep his diary. She agrees thinking she has the upper hand, but Akise wins every round, saying his diary told him what she would predict, making Hinata believe that he has a prediction diary. In the next round, she does what her diary tells her is not the correct answer but still loses to him, she lets Yuki go, but wants to play another round, so she keeps the diary.

Yuno gets suspicious, then reveals to everyone that Akise doesn't have a diary and was faking everything. Akise still wants to play one more round, so he makes an agreement with Yuno but she still doesn't trust him. He confesses to Yuno that he has a crush on Yukki, only angering her more. Akise figures out that the future is only what Yukki believes the future to be, so Yuno covers up his ears and tells him the false answer to which hand the coin is in, and the diary changes to be what he heard it to be. Mao, refusing to give up, attempts to stab Yukki, but Yuno hits her first. Hinata cares for Mao while she is unconscious while everyone else escapes. In the end, everyone escapes.

Akise, with the help of Kamado, went to see Deus asking if it was really possible to bring people back to life. Deus confirms that it is indeed impossible, he realizes Yuno had been lying to Yukki and he goes to warn him. Deus stops him and tells him that he is not a real person, just an observer meant to keep track of everything while he was dying. Akise couldn't believe that he had no free will, while Deus asked for proof that he had some. He claimed that his love for Yukki was real, but Deus said it was all fake. but Kamado brings Akise back with the detective diary, proving he has his own free will. Deus accepts this and lets him live.

Akise goes over to find Yukki, but soon realizes he's too late. Yukki had already killed Hinata, Mao, and Kosaka thinking that they betrayed him. Despite this, he walks over to Yukki, saying that he should have killed Yuno a long time ago. He tries to shoot Akise, but his gun was out of bullets. Akise theories that Yuno was using Yukki to become a god once Kamado died. Then, Yuno arrives and in an attempt to provoke her, he kisses Yukki. With his plan working, he goes over to Yuno to finally face her off in one on one combat. He uses a metal pipe to try to defeat her, but Yuno gets the upper hand and slices his throat, who tricked him into destroying the fake diary. he looks over to the diary and instead of Yukki, it says Amano, so he deducts it was the "real" Yuno's diary. At first, he thinks it's impossible, but comes to the conclusion that Yuno already won and she came back to play as a contestant again. He couldn't speak due to his throat being sliced, but he had to warn Yukki somehow. He used his phone to show Yukki the truth, but Yuno realizes this can cut off Akise's head.

Quotes
"Don't take this the wrong, but your shaking is adorable." Akise to Yukki

"My love for Yukiteru is more than just a friend." Aru Akise

Fanon
This ship is one of the most popular ships in the fandom. It's the most written about pairing on Ao3. It's mostly rivaled by Yukiyuno, the ship between Yukiteru Amano and Yuno Gasai.