|Relative||Rino (Younger Sister)|
|Manga Debut||Chapter 7|
Ren (蓮,Ren), also formerly known as the Gentōryū(嚴濤竜; lit. Stern Billow Dragon) during her time at Nangokuren High School. Being the elder sister of Rino, Ren almost achieved supremacy at the violent school just before her graduation and had a fierce rivalry with Hatenko Meru, before befriending her.
Ren is a tall figure with grey hair tied in twin pigtails,and like her sister she also has green eyes, along with another tie wrapped around her left thigh. She also often equips her sword as her main weapon.
As one of the toughest warriors, Ren is serious whenever she fought anyone stronger than her. She is also has a habit of changing her clothes during battle whenever her clothes are torn (even with the smallest tear). Despite her strong integrity as well as toughness, Ren has troubles with men due to her assumptions that men are perverse beings (which she claims that all men are trying to flirt with her, which she considered as vulgar). As a result, she cannot even speak to boys face-to-face and turns away from them, though she doesn't seem to have any problems with disrobing in front of Rintarou without any feelings of shame.
However, due to her friendship with Meru, she has taken an interest in Rintarou, as well as his skills.
At some point Ren joined Nangokuren High School and attended the school for 3 years. During her third year, she had fought against Meru and then became friends with Meru. Her fight with Meru would also inspired by the young Kyōka, who was a bookworm at her time. While surrounded by a bunch of thugs in a hidden ally and have them beaten without any effort, Ren would see Kyōka come at her to oversee the problem. Just as Kyōka would sense a brute is approaching from behind , Ren would tell her the instructions of dodge and counter attack against the Brute, which she witness the junior managed to give a brute a strong blow. Seeing that the book worm has the talents of a warrior, Ren would give her a compliment and encourage Kyōka to seek her own path while issue a battle against Kyōka.  Sometime later, Ren and Meru had fought one last time which result in Ren's victory. Ren then introduces Meru to her sister Rino and have her work with Rino.
Encounter and Rivalry with the Tiger
After defeat Rintaro Marokichi using his "eel". With the advent of Meru ask her the reason he's here to which she replied that I wanted to see as "Rin-chan" and she wastes no time telling him he is tested before it and accepts it takes. He asks her to take care of Rino threat but he can not make her his wife. Subsequently it without feeling uncomfortable stares with a smile so Meru teases saying "put his eyes on someone fussy" and "if she wants to become betrothed" to what blush, arguing that not say that crap and stop joking. Rintaro notifies that from now on will come more often to nangokuren to Meru says what you want to see Ren again Rintaro, blushes and imposes silence. When Rintaro told him that would not be a while you quickly wonder why, but after that Meru express her disappointment, she told him not to bother him and started a fight. Seems to show an attraction to Rintarou to not behave as it does with the other guysMeru talks to Rintaro and Ayane about Ren and how she is the older sister of Rino and how she almost conquered Nangokuren High School.
It is later shown that Ren began her covert return to the academy at the end of the while watching Rintaro from above. Unknown to her, Ren's presence was . Ignoring Rintaro's question, Ren would glide away with her blade and the chase begins until they reached the courtyard. She then sliced the statue in pieces and tossed a barrage of boulders towards Rintaro. While standing away from the rubble, Ren noticed that Rintaro escaped the barrage and assumed if his has used the "earthworm" skill. Even with Rintaro interrogation, Ren digressed Rintaro question while changes her clothes immediately after her's tore a little. After changing clothes, Ren told Rintaro that he stared too long while blushed.
During the conversation with Rintaro, Ren is receive a phone call from Meru about her odd conversation before she hung up. She then tells Rintaro the reason for her to have troubles to men is because she thought men are trying to flirt her, which she considered vulgar. Ren was welcomed by all the girls in the academy and reunited with the Year 3 students (Misa, Choco and Kyōka). She then "helps" Rintaro in his search for the culprit behind the underwear theft by taking one of the underwears to him, much to Rintaro's displeasure.
After Rintaro defeats Marokichi by using his "eel", Meru arrived and asked Ren regarding her reasons to be in the school, to which she replies that she wanted to test "Rin-chan" as a worthy inheritor of the "Covenant of Hagen" and she wastes no time to tell she acknowledges Rintaro's merit. Ren asks him to take care of Rino, but threats Rintaro to not make her sister his wife. Subsequently, Ren stares Rintaro with a smile without feeling uncomfortable, so Meru teases about Ren herself want to be Rintaro's wife, to what she blushes strongly. Ren recomposes herself and notifies she will come more often to Nangokuren (to see Rintaro, according to Meru). However, Rintaro told her that he would not be in the school for the summer vacations. Meru express her disappointment, Ren scolds her for bothering Rintaro and they start a fight, while Rintaro go away from them.
With the war for the royal seal between 2nd year and 3rd year students causing havoc, Rintaro stops Kyōka and Rino's fight and announces his application for Dragon. Along with Meru, Ren arrives to test him again and, once more time, recognizes Rintaro as someone worthy.
Ren was once the strongest student at Nangokuren High School and had almost conquered the school.
Expert Swordswoman: Ren was shown to be an excellent swordswoman and was able to hold her ground against Meru. When Ren returned to Nangokuren High School she displayed swordsmanship that utilizes spinning motions where she effortlessly destroyed concrete structures around the school when Rintaro had pursued her.
Keen Analysis: Ren is very observant and perceptive as shown when she was the only one able to deduce the mechanism behind Rintaro's Sumibi Gyūkaku technique being similar to a stuck knife splitting a bullet when it's shot at the knife while all the other observers were puzzled by the technique's execution.
Dual Headed Broadsword: Ren wields a dual headed blade that she was able to wield perfectly into a battle. The blade also contains a compartment that she uses to store her clothes for her to change with. Interestingly, her signature weapon also served as her odd transportation and glides away.
- Ren's name is based on the water lotus, the Sacred Lotus, which is also a sacred icon of Buddhism.
- On the Tankōbon cover for the fourth volume Ren's eyes appear light blue, where as in the color centerpiece for Chapter 18 they are green.