Akane Tachibana (立花 茜 Tachibana Akane) is a guest character from episode 16 of Ultraman Cosmos.
One day while returning from school, her classmates decided to voice their dreams. Akane expressed her amazement for whales and wish to swim with them. This was met with criticism, especially from Kota as it forced her to return home quickly. Because of this, Akane turned into a recluse and refuse to go to school out of depression.
While sulking in her bedroom at night, the Chaos Header took interest in her growth of negative emotions and materialize it in the form of the illusory whale as she named it Jirak. As she continuously staring at the whale, Akane's negative emotion became intense, so much so that she exhibits ESP abilities. Musashi tried to reason with her but by that point the Chaos Header's influence resulted with both the human and the illusory whale fused into Chaos Jirak. As Cosmos was struggling with the Chaos monster, Kota voiced his apology and promised to help Akane in achieving her dream. This caused the light virus to lose grasp of her and dissolving Chaos Jirak.
The next day, Kota lead his classmates to provide their support for her recovery while each bringing their whale-related gifts for Akane.
- As a result of Akane, Chaos Header started to harvest negative emotions, which lead to the formation of Chaos Header Iblis and eventually Chaos Darkness through their mutual hatred for Cosmos.
- She is modeled by the episode's writer Keiichi Hasegawa as a resemblance to Yapool's human victims of his Choju experimentation from Ultraman Ace. An example includes Garan with Mushitaro Kuri, Takai with Cowra and Yoshiko with Mazarius to name a few.
- Hasegawa would later write for the 2018 Tsuburaya and Trigger collaboration anime SSSS.GRIDMAN, which featured Akane Shinjo as a secondary antagonist. Like Tachibana, Shinjo is implied to be a recluse who has troubles with real life and found solace in otherworldly beings who's interest was to harvest the girls' negative energies to empower themselves. As with Jirak/Chaos Jirak, monsters crafted by Akane Shinjo are also driven by her negative emotions.