The following article contains information that may be of great importance in the series, read at your own risk.
Here you can find all the relationships that Aya Asagiri formed, with the other characters of Mahou Shoujo Site.Tsuyuno spent the night at Aya's place, etc.) but as the series goes on, it was shown that they deeply care for each other, and have a sister-like relationship. They kiss at the end of Chapter 54, indicating their feelings for each other are romantic.
When they were fighting against Sarina, Aya said that Tsuyuno always protected her, and that it was time for Aya to protect Tsuyuno. This made Tsuyuno very happy even though it wasn't obvious by her face. She also thanked Aya for hearing her words about her being her first friend which Aya was embarrassed after saying it.
When it was revealed that Tsuyuno had little time to live, Aya broke down, and became sad. Tsuyuno apologized for not telling her sooner, and told her not to worry. Aya admitted she knew Tsuyuno had few days left to live and said that she invited everyone to the beach to make good memories. Aya invited Tsuyuno to hang together to make good memories. When Tsuyuno asked to stop, they both cried because if they make more good memories it will only be painful. The two cried, Aya hugged Tsuyuno and said that she always wants to be with her forever and doesn't want to say goodbye. Tsuyuno replied that she always wanted to be with Aya too, and whenever she is with Aya, she feels happy and told her how much stronger she has grown and teased that she's still a crybaby and Aya teased Tsuyuno that she is crying also which Tsuyuno replied stupid. .
In Chapter 55 of the manga, Tsuyuno used her stick for the last time. She told Aya that she has grown stronger before turning into an admin. Chapter 86 reveals that Tsuyuno's death traumatized Aya to the point that she is now mute. During this scene, Rina states Tsuyuno was a very important person to Aya.
When Kaname obtained Nijimi's stick, everyone's lives feel into danger. When his face was fractured by Asahi Takiguchi, he tried to find Kosame Amagai for her healing stick. Once he entered the home of Sayuki Ringa, he proceeded to kill her bodyguards and enter the room the girls were all in. He proceeded to make everyone sit and watch as her took everyone's sticks. Aya told Kaname that she absolutely hated him, he told her that wasn't a very nice this to say to her brother and stomped on her, Sayuki soon cutting in telling him that what he just did isn't right. He also drank Aya's blood which had the effect of the healing stick on it, Rina looked disgusted by this.
Mrs. Asagiri is a kind and loving mother to Aya, unlike her father.
She's shown worrying about Aya and caring for her, everything a basic mother should do.
When Aya transferred to Sarina's school, Sarina always helped Aya. Aya was too shy to thank her, and this made Sarina believe that she is only letting people down and begins to bully her. She is one of the main reasons why Aya became a Magical Girl.
After Sarina recovered from her cut on the neck, she decided to ambush Aya and Tsuyuno at an apartment and told Aya hurtful things while using her stick. Aya then finally let out her feelings after being bullied verbally and physically which Sarina told her to shut up and called her a hypocrite, when the apartment was collapsing Aya used her stick to save Sarina. Sarina said that this doesn't change anything and didn't attend school.
When Nijimi died, Sarina comforted Aya but in the tough way and telling her that crying won't change anything. When she and the others died and Alice Misumi rewind the bombing that got them killed and together with Alice, told them to be in a far away place to talk about something. Aya told the others that they are her comrades which Sarina said that they aren't and pointed at her cut and told them that she'll never forgive them for it.
They first met when Aya teleported Nijimi somewhere and talked about Magical Girls. Nijimi invites the Tsuyuno and her to her home before running back to Dog's play meet and greet. Nijimi is thrilled to have other Magical Girls and even gave them nicknames "Ayapi and Tsuyuyu" and went to her floor. Nijimi then shows her stick and the ability of it then when asked about if she met any other Magical Girls before, she told them about Mikado Ikemata and let her "bad apple side" out. Aya and Tsuyuno got worried and lied to her for Rina Shioi's safety.
When Nijimi died, among all the other Magical Girls, Aya was the one who mourned the most and told her that their time might be short but it was amazing and she requests her to watch her from heaven. Her death might be the reason of Aya's growth and fearlessness in the series.
When Aya was skipping school due to her guilt and grief, Makoto would always come over to her house to deliver her homework. Once, he tried comforting Aya, telling her that she always has someone to talk to. She simply responded with "Thank you..".