Shinirai

Shinirai is the femslash ship between Karai and Shinigami from the Teenage Mutant Ninja Turtles fandom.

Canon
Shinigami and Karai are really close friends. The two of them met each other in Japan, a long time ago. They also work as a team. Throughout the scenes featuring Karai and Shinigami, Shinigami is seen to be tenderly touching Karai's shoulder and comforting her. She is clearly very close to Karai and trusts her judgement.

IWhen Karai meets the turtles and April, she introduces Shinigami as a close friend to them. Shinigami is also her second in command. Shinigami seems to trust Karai and has respect for her as she refers to Karai as Senpai and follows her lead. Shinigami is also shown to care deeply for Karai as she goes from blowing a raspberry at the turtles to looking at Karai sadly when Karai's shoulders slump. In Season 4, Episode 16, Broken Foot, Shinigami and Karai are once again seen together and work together to take down one of Shredder's buildings. Despite being interested in the money, Shinigami still lets Karai do what she wants with it.

When Shredder comes to confront Karai, Shinigami fights with Karai to take down Shredder yelling at Shredder that she will take him down for all the things he's done to Karai. When Shredder has Shinigami knocked out, Karai willingly surrenders to keep Shinigami safe. Shinigami even pushes others out of her way so she can get to the unconscious Karai. She then thanks Leo for saving Karai and eagerly agrees to keep watch over Karai while they wait for the ambulances. She even attends Splinter's funeral despite not having a close relationship with him, probably out of respect for Karai who could not make it.

Behind the Scenes
Peter Di Cicco, one of the writers of Teenage Mutant Ninja Turtles 2012, has actively shown his support for the ship referring to them as "ninja girlfriends" in several tweets, stating that Karai and Shinigami are his OTP, talking about how Shredder and Splinter would argue on who get's to walk Karai down the isle at her and Shinigami's wedding and also talking about how he wishes there was an entire series about Shinigami and Karai "hooking up" and going on adventures. In another tweet, he even refers to Shinigami as "Karai’s girlfriend."

Fanon
Shinirai became a popular ship after Shinigami's debut episode as it was a better alternative to Leorai. Though there isn't anything canonical in the show fans have pointed out that Shinigami is shown to be touching Karai quite tenderly and they seem to be very close even for friends.

The non-canon Ice Cream Kitty song video also featured Karai and Shinigami holding hands in what could be intrepid as a romantic gesture with a pink background.

On AO3, Shinirai is the most written ship for Shinigami and the second most written for Karai.

Fandom
FAN FICTION