The Invisible Blade (見えざる刃, Miezaru Yaiba) is the 10th episode to the Munou na Nana (Anime).
Nana is easily overwhelmed by her new nemesis Jin. After recovering from the wounds she sustained with the help of Michiru, Nana opens up to her about her checkered past. Eventually another murder occurs and Nana is not the one reponsible.
With Nana's cellphone in hand, Jin interrogates the distraught Nana, who tries to keep her cool. As Jin demands to know she tried to contact before he confiscated her phone. However, Nana refuses to disclose who it was and if Jin is curious to know who they were, then try simply transform into her. He doesn't, but instead fiddles with her phone and reads aloud "Potential Kill Count". Breaking free from her restraint, Nana escapes from the cave. She's stopped though by Jin who uses Moguo's Fire Talent against her. Caught up to her, Jin divulges that while he can use the people's Talent he transforms into, he still needs practice to fully utilize them. Standing before the beaten Nana, Jin has her disclose some information pertaining to her background, like facts about her family and her parents profession. Right before Nana passes out due to exhaustion, Jin gives her one piece of advice, that once more corpses start to pile up around the school psychopaths will arise and to be careful of that.
Afterward, Nana awakens in Michiru's room and is embraced by the relieved girl. Thankful for Michiru's compassion and care she leads Michiru to believe that it was Enemies of Humanity that Nana encountered and wounded her. Mistakenly, Nana lets it slips about wanting to get back at some villains which leads her to disclose her traumatic past where her parents were murdered by the hands of the Enemies of Humanity. Although Michiru attentively listens to Nana's story and tries to console her over her, Nana still believes that Michiru is a dangerous person with a dark side like Yuuka.
Time passes by and Kyouka talks with the homeroom teacher about the mysterious deaths that have recently occurred during, Yuuka, Shinji, and Kaori's funeral. Kyouka pushes the Homeroom Teacher to allow him to speak to his superiors when he contacts them about the deaths of the three students. Nana is in audible range of the conversation and has a brief flashback of when she was interrogated about her parents death. Once the funeral was over, Nana returns to her room and is visited by Jin. He claims that he's happy to see Nana has recovered since last they've met. Nana states that Jin could have transformed into Michiru and use her healing powers to heal her injuries. However, Jin couldn't as that would expend his life force, revealing that he suffers from the users weaknesses he transforms into. Using her phone as a bargaining chip, Jin tries to negotiate with Nana to allow him see another fragment of her soul, but Michiru intervenes. She enters Nana's room and Jin transforms into the cat to disguise himself. Sitting on Nana's bed, Michiru talks with Nana who discloses more about herself to Michiru who attentively listens, as does Jin. This goes on for the rest of the night.
The following day, Nana awakens to find Michiru sleeping on her bed and finds that Michiru was sleeping on her bed. Abruptly, Kyouya enters the room and leads to the two to the boys dorm area where the dead body of Ryuuji Ishii was. Although Kyouya suspects her as the culprit, he plays it coy asking her how to approach this as she's the Class Rep. On the other hand, Nana wasn't the one who killed Ryuuji.