Mastermind Kyoko Kirigiri

Mastermind Kyoko Kirigiri
In her AU, Kyoko Kirigiri was the Mastermind. Unlike Junko, Kyoko actually has a reason for wanting everyone to feel despair. She wants revenge on her dad, who left her when she was young. It started off as just revenge on her father, putting him in a rocket and leaving it to fly away and crash back down, but then she found that she actually liked the feeling of others' despair, so she started the killing game.

Kyoko, being the Ultimate Detective, convinced the other survivors in the 6th Class Trial that Junko Enoshima was the Mastermind, but when they voted, Kyoko revealed it was actually her and she then executed every single one of them with the "After School Lesson" execution. Except Makoto Naegi, because she was deeply in love with him, reverting to a yandere stereotype.

Kyoko then cleaned it up and kidnapped the next batch of Ultimates for her killing game.

All the survivors except Naegi died in this AU.

Partners
Kyoko Kirigiri briefly worked with Junko without revealing that she is the mastermind. This also helped whom she tricked everybody saying that Junko was the mastermind.

Makoto Naegi
Makoto was one of the weakest at the start of the game with Chihiro and Hifumi, but with every class trial Naegi started to become more hopeful. This posed as a huge problem to Kyoko. But Kyoko then had a mad crush on him and determining to keep him safe so he was the only survivor.

Byakuya Togami
Byakuya trusted Kyoko with any information he found out about both the games and the mastermind. He obviously never suspected Kyoko to be the mastermind however. Byakuya was the most frustrated about Kyoko being the mastermind.

Aoi Asahina
Hina was friendly with Kyoko and trusted her.

Junko Enoshima
Junko worked with Kyoko with things like Monokuma and another stuff, like a partner but was then executed by Kyoko who lied and said she broke a rule.

Celestia Ludenberg
Celeste was one of Kyoko's "best friends" who even told Kyoko her real name (Taeko Yasuhiro) and told her about her dreams. Celeste even told Kyoko that she was a witch, which Kyoko already knew because they were dating before she became a revenge-seeking Ultimate Despair. Celeste was probably the only one Kyoko felt bad for executing.