WARNING: The following contains spoilers for Talentless Nana, Episode 12, "The Invisible Blade Part 3," now streaming on Funimation.
One of Nana’s biggest defining traits is her ruthlessness, but throughout Talentless Nana, a series predicated on the revelation that Nana isn't a hero at all, she slowly develops a surprising soft spot for the kind-hearted healer Michiru. Nana continues to look for excuses to explain why she kept Michiru alive, but in Episode 12, she is finally able to admit to herself that she simply cares for Michiru and does not want her to die.
At the end of Episode 11, Nana finds Michiru passed out in the bathroom. Michiru fainted after healing a wounded wild cat that Jin (disguised as a cat) brought to her. Michiru’s power requires her to trade her life span for healing, and it appears that she may have used up too much of her life energy so she became ill.
Nana tries her best to help treat Michiru’s condition, even breaking into the diner to steal food and asking Kyoya for help. Nana knows it is a good time to commit more murders since Kyoya is tied up with investigating Ryuuji’s murder, but she does not want to leave Michiru alone. Fuuko offers to watch Michiru for Nana, but she turns Fuuko down since Fuuko is still the biggest suspect in Ryuuji’s murder, so she wants to protect Michiru from a potential killer. Nana’s actions suggest that she now values Michiru’s wellbeing more than carrying out her mission.
After Michiru wakes up, she shares her past with Nana, and this is when Nana finally understands why Michiru insists on healing others even though it could cost her own life. Michiru was bullied by her former classmates after she used her powers on a popular boy in school. The person that defended her was Hitmi, a classmate who rarely goes to class. Hitomi encouraged Michiru to use her powers to help more people. Unbeknownst to Michiru, Hitomi had cancer and died shortly after Michiru found out about her condition. Michiru’s powers cannot be used to treat illnesses, so she devotes herself to healing more wounded people in order to make up for her regrets.
Nana is shocked by Michiru’s kindness. She is beginning to doubt the government’s data about the potential number of kills that each superpowered person will commit. The numbers show that Michiru will kill 150,000 people in the future, but it is hard to imagine that someone with Michiru’s powers and temperament would commit such atrocities. Jin also thinks the numbers are meaningless, he knows it is just a manipulation tactic used to control Nana.
On the other hand, the government’s true intentions are slowly being revealed. They initially used Nana as something disposable and did not expect her to perform as well as she did. They are now sending Nana’s teacher onto the island to inspect the class because the island sent out distress calls for help after multiple people died. The way Nana’s teacher Tsuruoka is introduced shows that he is a very menacing presence, most likely a part of the military, although he refers to Nana as “like his family,” so there could be more to be uncovered about Nana's past.
With only one episode to go, there are a lot of loose ends the series needs to tie up, chief among them is the identity of the new killer, who is clearly a psychopath and has been killing animals in the forest, including the cat that Jin asked Michiru to heal. Jin knows who he is and warns him not to harm any more animals, but still chooses to let him go. It's possible that the killer will escalate into killing humans in order to compensate.
