in the end, it's all other people's business

Inbox: text, voice, video, etc.

Sasuke checks his device inbox regularly, though he may not reply the instant he receives a message. He's turned off the notification volume. He can't be a ninja if his device randomly makes noise without warning!

Mr. Tori?!

If Mr. Tori, Sasuke's crow familiar, recognizes your character as a friend, he'll deliver small notes and items to Sasuke. Just hand them to him.

Housing

Living with Zenitsu Agatsuma, Misuri Kanroji, and Giyū Tomioka

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Sasuke has the ability to shapeshift into other people. It's appearance only. He doesn't gain their voice, powers, memories, and so forth. For the most part, Sasuke would only do this for playful fun in front of the very person he shapeshifted into. (And anything more than that, I would plot with you first.)

If you are okay with Sasuke possibly transforming to look like your character, please leave a comment below and any other limits you'd like to put.

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i.e. Sengoku Barasa plays fast and loose with timelines and relations, and so am I.

While looking at some fanart, I saw a comic that had Yukimura calling Sasuke "Mikumo Yoshiharu." That led me down a very interesting rabbit hole that I decided to adapt into a SenBasa style background.

There are multiple theories as to how the character "Sarutobi Sasuke" can to be. The English Wikipedia article only mentions Kozuki Sasuke and Sarutobi Nisuke as possible sources, and searching for those names seems to only circle back to Sarutobi Sasuke and little else. That's doesn't create much for a possible background.

However the Japanese Wikipedia article for Sarutobi Sasuke also mentions Mikumo Yoshiharu as a possible model. This connects him to other people and places of the time, and he's mentioned on their pages as well. Yoshiharu was the son of Mikumo Katamochi, brother to Mikumo Shigemochi. Both served the Rokkaku Clan as retainers. Katamochi died in a battle against Azai Nagamasa, and the Mikumo (under the Rokkaku Clan) were taken over by the Oda Clan. Shibata Katsuie defeated the Rokkaku Clan completely after.

The Rokkaku Clan lived in Omi and near the area where the Koga-Ryu resided. Sasuke is a koga ninja. Two from the Rokkaku Clan (Rokkaku Masayori and his son Takayori) escaped with their lives during a battle against Ashikaga Yoshihisa with the help of Koka (Koga) samurai who pretty much became koga ninja. Togakushi Village is also in the area.

Bonus fun fact, the mon for the Rokkaku Clan looks a lot like the mon for the Takeda Clan. Just for reference sake, the Mikumo Clan uses this mon.

Using all that quick and dirty research, this is the backstory I came up with for SenBasa's Sarutobi Sasuke. It's historically inspired but is fast and loose with timelines. Roles and events become merged and attributed to related, more prominent characters. (Basically, the named ones in SenBasa.)

( Yoshiharu and the fall of the Mikumo and Rokkaku Clans )

( Sasuke and the fall of Togakushi Village: Sarutobi Sasuke's Retsuden Chapter Summary )

The short version is bitty Sasuke was Mikumo Sasuke Yoshiharu, who became a ninja after barely surviving an Oda attack... only to lose his ninja village to an attack from within organized by his then best friend and his teacher. He became Sarutobi Sasuke after becoming Benmaru's (Yukimura's) kagemusha and ninja.

Sasuke could really use some hugs.