Mitsuki's Rainy Day

Synopsis
On a rainy day, Mitsuki finds Mikazuki, who leads him to an injured and bleeding man. The man asks if Mikazuki is his before passing out. The man wakes up in Mitsuki's apartment, having been given first aid. He thanks them both and introduces himself as Samidare. He finds it strange that Mitsuki didn't ask why he was bleeding in an alley. Mitsuki says he doesn't care either way, unless Samidare wants him to ask about it. The following day, Samidare's injury is healed, and Mitsuki asks if he has to go somewhere. Samidare explains he's come to visit his little sister, who works at a big company in Konoha. Mitsuki compares his pride in his sister to Boruto's in Himawari. However, Samidare says he's not a good big brother. Samidare wants to thank Mikazuki, and buys him a new collar with a bell. Mitsuki notes he has a way with cats, and Samidare says his sister, also named Mikazuki, had one. Samidare leaves as Boruto and Sarada approach Mitsuki, telling him they've been summoned for a security mission. Kōtarō wants them to protect the president of the Kaneki Corporation, a chemicals corporation on par with the Kaminarimon Company. He is the likely next target of the Rainy Day Killer, a serial killer who always kills his victims with a thin, sharp tool on a rainy day. All of the victims so far have connections to an accident on a Kaneki chemical plant years prior. At Kaneki's residence, he surprises Kōtarō by claiming he remembers nothing of the incident, and refuses the security detail, believing his own bodyguards will suffice should the need arise. Kōtarō has Team 7 guard him secretly from a distance. It begins to rain. They spot someone approaching, but Kaneki's bodyguards fall over before even being attacked. The intruder makes his way to Kaneki. He tries leaving him Kaneki, but Boruto and Sarada engage him. Mitsuki recovers Kaneki, and pursues the Rainy Day Killer. Mitsuki attempts to attack him with snakes, but they're killed from a distance. The killer escapes by jumping into a river. Mitsuki meets Samidare the following day, and asks if he was able to meet his sister. He says he did, but she yelled at him. Mitsuki notices he's a shinobi, and he claims he used to be, having quit after being an obedient dog for years. Mitsuki asks him about his past as a shinobi, and Samidare evades the questions. He says he quit because he wasn't there for his family when they needed the most, and now it's too late. Kōtarō and Team 7 review what they know about the case. Mitsuki notices something in the records of the chemical plant accident. Policemen inform them Kaneki has been kidnapped, even though it's not raining. Kaneki wakes up with the killer at Mikazuki Amaashi's grave. She was the developer of the project that resulted in the accident, because Kaneki pushed it forward to keep ahead of the competition. She died and lost her reputation, while Kaneki just got wealthy. Mitsuki exposes the killer as Samidare, and wonders if he's killing those who ruined her sister's reputation. Samidare says he only wanted the truth at first, knowing Mikazuki wouldn't have gone ahead with a dangerous project. However, they just made excuses and disparaged the dead, so Samidare killed them. He asks Mitsuki not to interfere, but as a Konoha shinobi, he has to. Mitsuki believes Samidare to be in a dilemma, as he knew Mitsuki was a shinobi, having seen his forehead protector, but mentioned his sister's name anyway, something that could lead to someone stopping his revenge. Samidare says he has no problem with his resolve. It begins raining. Samidare uses his Water Release, which Mitsuki blocks, and counterattacks with Lightning Release. Mitsuki explains how he deduced how Samidare's jutsu worked. Samidare tries killing himself with his jutsu. The next day, the investigation on the plant accident is reopened, and Mitsuki visits a comatose Samidare in the hospital, putting the collar he bought Mikazuki on his wrist.

Trivia

 * This was the first episode to air in Japan after the anime's hiatus due to the COVID-19 pandemic and the subsequent production shutdown. The previous episode aired three months before on April 26th, 2020.