Later in the Lab

Later in the Lab (その後の研充室, Sonogo No Ken Mitsuru-shitsu) is a bonus chapter of Onimai! I'm Now Your Sister. It was originally published in EX Special which was released on December 31, 2018.

Summary
Mihari has a chat with her faculty advisor Chitose Azuma about Mahiro.

Plot
While Mihari is working in her college lab at her computer, she cracks her fingers and notes that she has just a bit more to do today. Out of nowhere, a women with messy hair grips Mihari's shoulders from behind and calls out her name with a devious smile. Mihari freaks out a bit when this happens.

Turning around, she realizes that it is her faculty advisor Chitose Azuma and reprimands her for sneaking up on her again. Chitose laughs a bit and apologizes. A caption reveals that Chitose is Mihari's senpai at the university looking after her research.

Chitose asks her how it went, and Mihari says that Mahiro has safely become a middle schooler, all thanks to the framework that Chitose set up. She also notes that she seems to be getting used to it. Chitose smiles and notes that that's the most important thing, but notes that if that's the case she'd be very curious about Mahiro's life at school.

She tells Mihari that her last report was interesting, but to be sure to do the next report on Mahiro's life at middle school. Mihari notes that she's pretty sure that would be impossible, and Chitose sighs realizing that she's right. Chitose decides that she'll step in and help again, but Mihari tells her to stop with the crimes. She thinks to herself that it really feels like Chitose will do anything.

Characters

 * Mihari Oyama
 * Chitose Azuma

Trivia

 * First appearance of Chitose Azuma
 * Due to this chapter being published exclusively in EX Special, it has not received an official English translation or release, though an English fan translation is available for purchase at DLSite alongside the Japanese release.
 * The events of this chapter take place during the events of the previous chapter "Mahiro and the Uneventful Holiday", before Mihari returns home to Mahiro.
 * According to Nekotofu, the events of this chapter, it's predecessor, and the corresponding Drama CD take place after the events of "Mahiro the Own-Home Security Guard", and "Mahiro Helps Out". It also takes place before the events of "Mahiro and the Middle Schoolers" as Mahiro has not gone back to middle school yet as evidenced by her late night routines.
 * Mihari references how Mahiro recently started middle school again in "Mahiro's First Day", and it is revealed that Chitose was the one who dummied up the identification documents to allow it to happen.