Most of the romance is light yuri. Most of the other romantic relationships are intertwined with mahjong. The character form relationships by playing mahjong. The better the players are at mahjong, the stronger their relationships grow. And when the characters support each other, they play better mahjong. They love mahjong.
The most comedic character is interested in a male club member, although it's unknown whether she is flirting or simply teasing him. She also flirts with a female teammate and loves tacos.
- One of the most popular pairings in the series. Their relationship started off shaky, due at first to Saki stating that she didn't like mahjong and later allowing Yuuki to defeat her on purpose. They began to get closer after they promise to go to the national together. Since then they've had many moments together such as the firefly scene in episode 8, sleeping together during the prefectural finals, sleeping on the train together after winning the tournament, and the firework scene in episode 24. One of their biggest moments happened in episode 25. After being upset about what her sister told an interviewer, Saki leaves the hot springs. Nodoka takes her to a shrine to cheer her up. There, they exchange souvenirs and finally choose to refers each other by their given names as a sign of familiarity.
- One of the most popular pairings in the series. Also known as "BuCap" because of the girls positions as president or bucho in japanese (Hisa) and captain (Mihoko). Hisa and Mihoko had played against one another in middle school. Here Hisa complemented Mihoko's right eye which she was sensitive about. After Hisa didn't show up for the rest of the match, Mihoko looked for her the following year when she entered Kazekoshi. During the prefectural finals, Mihoko recognized her even though it was three years later and she had changed her name. At half-time of the leuitenants match, Mihoko rushes to the main hall to inform her teammate about Hisa's tactics, however Hisa did not remember her. After Kiyosumi wins the finals Mihoko offers her congratulations to Hisa. They did not meet each other again until the final match of the first day of the individual tournament. With Hisa ahead, Mihoko thought about losing but opens her right eye to use her power and win the game saying they are already walking different paths. During the duel, Hisa finally remembers her; and after the match tells Mihoko this and says they'll meet again. True to her word they meet again durin the final match of the final day. This time however it was Hisa's victory. After the match Hisa congradualates Mihoko on making it to the nationals. Later on Hisa sends out invatations to a combined training camp she wishes to set up. Mihoko ends up delevering hers personally and after a brief conversation, Hisa invites her to watch the fireworks. They are later seen on top of Kiyosumi's roof viewing the fireworks together. As of the nationals Hisa and Mihoko are seen much closer together than they were previously and it is shown that Mihoko will only open her right eye around Hisa.
- One of the most popular pairings in the series. Their relationship began when Tsuruga began to recruit new members to join the mahjong club. Momo joined them in playing online games but due to her lack of presence, refused to go to the club room. Yumi then set up a computer to tell her which room Momo was in and barged into her room. She then began to shout "I want you!" in the middle of the classroom. Momo having been amused by this showed herself to Yumi and joined the mahjong team. During the team tournament we see them going on dates and Momo declaring her love to Yumi. In the individual tournament, Momo wished to avenge Yumi's loss to Saki but wasn't able to get the victory. During one of the picture drama's we were able to see one of their dates. Here they ride the train to the beach and later feed each other at the hotel they stay at. Throughout their appearances Momo has shown great jealousy to anyone trying to get close Yumi.
- Kouko has deeply admired Sukoya since she won the national tournament years ago. Since she became paired with her during commentating, she always finds ways to embarrass Sukoya during the broadcast whether it be from overly praise her (like saying how beautiful or skilled she is) or saying something that implies something else (Toki's "first time"). These two remain close outside of broadcasting as shown when Sukoya spends the night with Kouko. In the Biyori, the two were looking at taking a vacation together.
-The only straight pairing in the series. Throughout the series Yuuki is constantly flirting with Kyou and making suggestive comments. Once she dressed as a maid and flashed Kyou what was underneath her skirt, although it didn't interest him. Later while walking home together, Yuuki wondered if Kyou was going to take advantage of her. Kyou has helped her out quite a bit in the series like bringing her last minute tacos, becoming the motor for her inflatable raft, and making her tacos during the national. During bus rides these two are seated together and are normally seen together.
- Their relationship began when Touka bought Hajime from her father and brought her into her household. Hajime considers herself Touka's personal maid and sometimes sleeps in the same bed as her and Koromo. After her match, Hajime refused to let go of her shackles stating that she felt closer to Touka and that when she did take them off, she was always right there with her. Later when Jun mentions the possibility of Touka getting a boyfriend, Hajime is visibly upset and says there is no way that would happen. Whenever Touka goes into her "cold" state, Hajime is seen to constantly worry about her.
- Their relationship stems from Kana's deep admiration of Mihoko. Early in her first year Kana asks Mihoko to walk home with her every day and to call her by her first name; to which Mihoko agrees. Throughout the series Mihoko is constantly looking after Kana, such as petting on her, encouraging her, and even washing her hair. Kana is always looking for ways to help Mihoko. Unfortunately, Mihoko's history with Hisa may render this relationship as one-sided.
- A few year ago when Hisa tries to revive the mahjong club she had difficulty bringing in people to stay. Mako arrived and it was just them until the first years showed up. Before the prefectural finals, Hisa thanked Mako for helping achieve her dream and they promise to keep on going together. Mako is one of the few who Hisa confides in and in the nationals Mako worries for Hisa when she doesn't seem to be herself.
Touka Ryuumonbuchi and Nodoka Haramura
- This stems from Touka's over active imagination and her one-sided rivalry with Nodoka. During the vice-captain match they played together, Touka imagine herself battling Nodoka in a shounen type atmosphere. However this takes a turn when Touka imagines that she caught Nodoka. She then proceeds to grope her breasts and start licking the side of her face. In the national she is more than overjoyed when Nodoka decides to cosplay as her maid. Later Touka tells her that if she loses she will make her her maid forever.
- Miharu has a deep admiration for Kana, even saying that she will always be a superstar to her. When they see their captain winning her match, they dance up and down holding each others hand. After Kana loses her match, she runs into Miharu's arms. Kana is seen being affectionate with her such as when she gives her the nickname Miharun and tells her to call her Kana-chan. She is also the one who picks out Miharu's glasses frame.
- As seen on a flashback, Shiro declines to eat with her classmates because she feels sluggish. When she leans back, she notices the new transfer student, Aislinn Wishart. That's when their relationship started. Shiro is the first person to understand Aislinn's drawings. The drawing that decided that Aislinn's going to join the team. Shiro was still on the playing area when Aislinn arrived. She asked her to carry her back to the waiting room but she declined by drawing a picture that said 'Screw you'. On the sergeants' battle, Shiro asked Sae if she could go home because she knows Aislinn would win it anyway. After her match, Aislinn was in tears but Shiro comforted her by saying that she'll be more tired if she cried. Aislinn is often shown seated beside or behind Shiro.
- One of the two most popular pairings in the Achiga-hen series and have been together since middle school. When they are first introduced at the national tournament, Toki is sleeping on Ryuuka thighs. In the anime after Toki's first match in the inter-high, Ryuuka was seen helping her to the waiting room. However Toki said she didn't need help, but relented and held Ryuuka's hand. In a flashback, the first thing Toki did upon awakening from an unconscious state was to grab Ryuuka's breasts to confirm she was awake. When Toki collapses after her semi-finals match, Ryuuka stayed with her until it was time for her match and even then had to be pryed away from her hospital bed. Toki then awakens and starts immediately calling for Ryuuka. Their bond is so strong that during the finals a fairy-like Toki appeared to Ryuuka and helped her. Also in an anime only conversation, Ryuuka and Toki have a conversation about going to the national similar to Saki and Nodoka's.
- One of the two most popular pairings in the Achiga-hen series. Mairu and Himeko have been together since middle school and share a strong bond. So strong a bond in fact that their mahjong abilities are intertwined. When ever Mairu uses her "reservation", Himeko will blush, her legs will quiver, and she will look as if she is feeling pleasure. They are constantly together and thinking of one another during their matches. In a brief flashback during the captains match of the semi-finals; they have been shown walking down the street holding hands, nestling their heads together, and has shown Mairu conforting Himeko.
- This pairing stems from Arata's deep admiration of Harue. After Harue's defeat at the nationals, a young Arata came by to say how cool she was and that she would cheer for her in the future. Nozomi then suggests that Harue give her and autograph but she says that her writing is awful. However after seeing Arata's sad face, Harue gives the girl her necktie to keep. Years later, upon hearing that Harue was playing professionaly, Arata gets excited and immediately looks up details about her. Arata is later shown blushing whenever Harue recognizes her in the club. At the national tournament, they share the same room. Later when Ako thought Harue was just using Achiga, Arata bodly defended her. During the semi-finals, Harue worried about Arata wearing her tie but Arata told her that she was there because of it and will take it to the finals.
-During the finals of the 12th Matsue Children's Mahjong Tournament, Rena states that out of all her clubmates, she will choose to root for Shino because she had come to admire Shino's crazy enthusiasm for mahjong. After the Children's National Tournament, she was the only one to notice that Shino was upset, and suggested taking her to the beach to cheer her up. After this, Rena has gotten quite physically close to Shino: her first reaction when scared, anxious, happy or even sleeping seems to be hugging or otherwise holding her.