Natsuo Kobayashi is a 17 year old tomboy in love with Rando. The grandchild of the monk Hifumi Kobayashi, Rando trains her in karate in his sophomore year. Devasted by hearing of Rando's death in a bus accident, Natsuo visits the site of the accident and goes to Seika High School to ask someone where she can lay down some flowers. She overhears Yuna talking to Dr. Manabe and finds out Rando is actually Yuna and is pretending to be Rina's twin sister. At first she is outraged about this and tries to out him as a man. After hearing his story she decides to let him continue, but wants Rando fall in love with her instead of Rina.
Natsuo is very confident in her fighting ability, but it does lead her to get into embarrassing situations. She's also aware that she can be a klutz at times, accidentally exposing her panties which usually leads to violent outbursts. Natsuo has her sights set on Rando and is determined to get him to fall in love with her.
- Rina Kurumi
- Natsuo considers Rina to be a rival for Rando's affection. She constantly tries to tear Rando apart from Rina in order to get him to fall in love with her. However, Natsuo does back down after Rando becomes upset at her frequent attempts to push them apart. Natsuo acknowledges that Rina and Rando are deeply in love with each other, even if Rina doesn't know that he is actually alive. However, Natsuo is determined to replace Rina as Rando's true love.
- Yuna Kurumi
- When meeting the real Yuna, Natsuo tells her about Rando's good qualities so that she would have a better opinion of the man who was pretending to be her for several months. Natsuo seems to have become good friends with the real Yuna, bathing with her at the hot springs on the senior class trip. However, Natsuo has a hard time telling the difference between Yuna and the fake Yuna, something she found out when Rando showed up in the hot springs.
- Masashi Rando
- Natsuo and Rando met about 3 years before the events of Pretty Face. Natsuo was 14 years old and hadn't gone through puberty yet. That and the fact that Natsuo's uncle Hifumi had simply introduced her as his grandchild led Rando to believe that she was a guy. While being trained by Rando at winter camp Natsuo developed a deep crush for Rando and was heartbroken to hear that he had died in a bus crash. When she first came to Seika High she attempted to ask where Rando's grave was located so she could burn incense sticks for him. After Yuna accidentally stepped on her foot, Natsuo headed over to the clinic. She hid under a bed to scare Yuna for stepping on her foot. While under there she overheard Yuna revealing herself to be Rando when talking to Manabe. Natsuo tries to confront the two about this but they both deny it. Natsuo tries to publicly prove that Yuna is actually a guy. However, after trying to fight him Rando does protect her from a falling potted plant. After Rando tells his story Natsuo decides to keep his secret. Natsuo is disturbed by the fact that Rando is living as Yuna, Rina's twin sister under the same roof and that Rando has a crush on her. Natsuo tries to get Rando to fall in love with her instead of Rina with little success. Natsuo's attempts to seduce Rando are suggested to have made her classmates think she is a lesbian.
- Nozomi Ueda
- During Nozomi's hospitalization, she gained a hatred for Natsuo when she heard that Natsuo was getting close to Yuna. When Nozomi returned to school, she competed with her for Yuna's affection. When Nozomi was kidnapped and threatened with rape by a gang of lowlives, Natsuo and Yuna helped free her. Nozomi fell in love with Natsuo for saving her and considers her a second love interest next to Yuna.