Six Enormous Mountains
|Hair Color||Golden blonde|
|Manga Debut||Chapter 2|
Keiko is an attractive young woman of average height, with blonde, shoulder-length hair that is tied into a messy ponytail and small eyebrows. She wears an open white buttoned-down shirt over a tight black tube top, as well as a dark coloured skirt with yellow lines over black shorts, light coloured shoes, and bandages around her forearms. Well-endowed, her cleavage is seemingly deep enough to store at least three snacks (a banana, an hot-bun and a large snack bar) that remain unseen until pulled out. Her breasts are quite big and along with Ayane and Makoto's breasts, Rintaro refers to them collectively as the Six Enormous Mountains.
Keiko is shown to be a laid back and relaxed person, often thinking very little of actions such as bringing huge boulders into the school for the sole purpose of throwing at people. Most notable is her obsession with food, often suggesting that they eat snacks as well as maintaining a one meal per hour lifestyle, claiming that she is still 'growing'. This goes as far as Keiko keeping a large stock of food hidden in her cleavage. She has also shown to care about Ayane's well-being, as she attacked Rintaro after misunderstanding the situation between him and Ayane in the bathroom.
The Persistent Disciple
Appearing behind Ayane on the first day of school, Keiko attempts a sneak attack on her leader by throwing a large boulder at Ayane and claiming she was full of openings. Despite this her attack is dodged, and the rock subsequently turned into a sculpture of a dragon by Makoto. Ayane then admonishes Keiko for bringing the boulder into the school, only for the gluttonous girl to laugh about how she thought it was the right size to throw at Ayane. Changing the topic to food, Keiko quickly pulls several snacks out of her cleavage despite Ayane reminding her its only 10 o'clock only for the former to claim that any time between breakfast and dinner is lunch. Makoto cuts in however, bringing up the rumours of Ayane taking on a master, with Keiko asking why she didn't talk to them first about it.
Seeing something out of the window, Ayane apologises to her friends before quickly leaving, causing Makoto to suggest they take a bath. Still protesting Ayane's decision, Makoto reminds Keiko that they can't overturn Ayane's decisions, but they should still see if the man she has decided to follow is worthy of Ayane's respect.
Later, both Keiko and Makoto enter the dormitory bathroom, stripped and ready to bathe, with Makoto complaining how the other has brought more food and the dragon sculpture into the bath. Taking notice of Rintaro, the two wonder why a man is in the bathroom before seeing Ayane crying behind him. Thinking he has done something to hurt their friend, Keiko immediately attacks Rintaro with the dragon sculpture, striking him with enough force to shatter the stone. Seeing the young man close his eyes, both Keiko and Makoto move in to attack again, only to have all of their strikes evaded. Seeing Rintaro run across water, Keiko asks in shock if he's a sage before being struck by the man's Gansai Suida technique, left paralysed by the attack.
Behind the two, a water pipe damaged by the attack suddenly bursts with a stream of boiling water rushing towards the girls. Unable to move, both Keiko and Makoto can only watch as Ayane uses her own body to block the searing water. Telling Ayane to move out of the way, their cries are ignored as the Ryōzenpaku leader refuses to run for the sake of her friends. Luckily, Rintaro is able to stop the flow of water and Keiko soon regains the ability to move and claimed the reason both she and Makoto see his caliber is for Ayane's sake, before rushes to Ayane's side when she collapses from exhaustion. Noticing Rintaro watching them, both Keiko and Makoto are furious about his stare and tends to teach him a lesson. 
The Disciplinary Squad
The next day, Keiko enters Rintaro's room along with Ayane and Makoto and demands that they get the training over with so she can go to the cafeteria. Arguing with Makoto over whether baths or snacks were more important to start the day, they soon realise Rintaro has disappeared from sight. As Ayane begins to call out for him, Keiko warns her that if she keeps yelling the Disciplinary Squad will come, to which Ayane then suddenly leaves the room telling Keiko and Makoto to follow her.
Later after the Disciplinary Sqaud is disbanded, she accompanies Ayane and Makoto to meet with Rintaro.
Meeting with the Tiger
Some time after Rintaro encounter with the Tiger, Keiko and her friends becomes a member of the audience to the battle between Rintaro and Meru in the Batsuzangaisei Ceremony where she witnesses Rintaro emerge victorious after he destroyed an old school building and the Ren Hall (albeit unintentionally) with a single blow.
The Day of the Event
Ren's Return & Ambush by the BeastSometime after the event, Keiko is joined the class swimming class while eating. After the class, Keiko and Makoto angrily accused the Virginity sworn Brothers for stealing Ayane's underwear, which she had cynic about the boys for their perversion about the girls and assume they are the culprit. As Keiko's blood boiled and wishes to beat the suspects with her fist, she is witnessed Rintaro decided to help the boys to clear their name with an unusual method: detective. Keiko and the girls was so speechless about Rintaro's passion about detective manga and novel, that she would claimed that Rintaro was delusional. Regardless, Keiko reluctantly entrust Rintaro's investigation for Ayane's sake while keep an eagle eye towards the "suspects" by tie them onto the pole; telling them that until Rintaro returns with his answers they are not clear from suspicions.
As Rintaro searching for the clues, Keiko would take her break under the tree. Just as she rest under it, Keiko sensed a deadly aura come from the tree and dodged away before the broken tree injured her thigh. She is then confronted the unknown Beast (who previously attacked Naomi) and going to battle against it despite her injuries. As she is about to investigate the defeated body and wonder what with him, Keiko is ambushed by the revitalized and awaken beast and she is beaten badly by it. Just as she is about to break, Keiko is rescued by Ayane in a nick of time. Before passing out, Reiko managed to strip the watch and give it to Ayane, which hold the clue about the Beast's true identity. Keiko is then sent to the Medical Infirmary and steepen Ayane's resolution to find the culprit as her retribution.
Expert Hand-to-Hand Combatant: Being a sub-leader of Ryozenpaku and thus a powerful subordinate of Ayane, of the Dragons, Keiko is a powerful fighter utilizing her powerful physical strength with brawler moves. Though even with Makoto's help she was no match for Rintaro.
Enhanced Strength: Keiko has been shown to possess a certain level of strength, being capable of carrying around boulders larger than herself with ease, as well as hitting people with said rocks with enough force to shatter them.
- Keiko Tijera Special (ケイコ・ティヘラ・スペシャル, Keiko Tihera Supesharu, "Tijera" is Spanish for "scissors"): 
|Ayane • Keiko • Makoto|
|Ally||Tachibana Rintarō • Okina • Shiryū Chō|
|Rival||Kagamiin Kyōka • Rino|