Teruaki Koyanagi

* (Giggles) Hello! I'm a Kamen Rider! Nice to meet you! - Teruaki to Sento in Kamen Rider Build Be the One.
* It doesn't matter if I would be the one who would destroy everything. As long as I have friends that will help me, I don't need to worry. - Teruaki to Renji in Zi-O
* Being a Kamen Rider doesn't mean it's all sunshine and rainbows. It's about taking risks and sacrifices. So, go ahead. Lash out at me for putting myself in danger because I know that you're worried about my safety, but you don't have to. I know that I'm going to die. It's who I am - Teruaki to Misora after killing Kazumi in Zi-O
Teruaki Koyanagi is the main protagonist of DZ2K's Kamen Rider Zi-O. She is a young, cheerful and energetic woman who's in love with the Kamen Rider series.
== Story ==
Born in the year 2000, Teruaki received an message from a mysterious girl, saying that the Heisei timeline is in jeopardy. With the Ziku Driver and Jikan Watches, Teruaki has to travel to the other Heisei worlds in order stop her future self from destroying the future.
=== Kamen Rider Build Be The One ===
During her adventures in the world of Build, Teruaki discovers that Sento has been framed by the Blood Tribe. 
=== World of Build ===
The Blood Tribe was defeated, but Evolto revealed his true colours and challenged Sento to a fight on top of Pandora Tower. Sento asks Teruaki to help him defeat Evolto, of which she agreed.
Despite Misora's pleas, Teruaki kills Kazumi after he was affected by the Grease Blizzard after effects though she had no choice due to him allowing her to lay the final blow. 
=== World of Ex-Aid ===
After helping Sento with the Lost Fullbottles, Teruaki traveled to the World of Ex-Aid, right before Dan Kuroto's revival.
=== World of Ghost ===
Teruaki woke up in the world of Ghost, in front of a chamber. From there, she met Kamen Rider Necrom, or known as Kamen Rider Dark Necrom Pink.
=== World of Drive ===
(TO BE ADDED)
=== World of Gaim ===
(TO BE ADDED)
=== World of Wizard ===
(TO BE ADDED)
=== Final World ===
Teruaki, along with the 19 other Heisei riders, were sent to 50 years into the future and discovers that the future has in fact changed. 
== Kamen Rider Fighters ==
Teruaki, along with Renji Akiyama, aka Kamen Rider Gates, was pulled from their own world to the Fighters universe. From there, she met Sento Kiryu, who was shocked of her appearance. 
== Personality ==
Teruaki is cheerful, bubbly and energetic. She is rather described as a 'Optimistic Master of Time of Space' by Renji. At times, she has a childish demeanor, to Renji's annoyance. 
However, on some occasions, she has a darker, serious, and twisted side, as a result of her childhood, of which she witnessed her own mother kill her father in front of her eyes.
Due to her troubled past, Teruaki won't mention about her mother. The only time that happened was when Gentaro accidentally uncovered a secret of her past.
Despite those traits, she does tend to break down often when she told Sento that she was the one that killed Kazumi.
== Relationships ==
* Renji Akiyama - Without knowing that Renji is from the future, Teruaki forms a bond with the young knight after he rescued her from the Time Zombies. 
* Sento Kiryu - When she first met Sento, she was completely surprised of his reaction.
* Misora Isurugi - Despite some issues between the two, Teruaki and Misora have a stable relationship, but that all changed when Teruaki killed Kazumi though she had no other choice. This almost severed the bond between them but then, Sento 
== Killed Victims ==
* Multiple Time Zombies
* Kazumi Sawatari - Was forced to kill him after he was consumed by the aftereffects of the Grease Blizzard, turning him into a mindless zombie. 
* Gou Shijima - Forced to use him as a shield when the Angel Roidmunde went insane and started to wreck havoc on the world of Drive. This was moot, however, when Gou wore a bulletproof vest. 
== Trivia ==
* Teruaki is modeled after Yukari Taki, who portrayed Sawa in Kamen Rider Build. She's voiced by Akemi Kanda and Cherami Leigh in both Japanese & English.
*Teruaki has some similarities to Satou Matsuzaka from Happy Sugar Life: Both have bad childhoods (Teruaki's mother killing her father and Satou's Aunt abused her)