After learning that she was a great cook, Kokichi asked Kirumi to be his "mom", and then proceeded to assume she would make him food whenever he wanted despite Kirumi expressing a strong disliking for being called a mom.
In Chapter 2 of the game when Gonta Gokuhara was going around forcefully taking his classmates to his research lab to have an insect meet-and-greet, Kirumi was able to stop him from taking her with seemingly her strong willpower alone, Kokichi was amazed by this, acknowledging her skill, then pointing out to everyone else that at least one student was worthy of being called an Ultimate.
Later, Kirumi caught Kokichi sneaking out at night and interrogated him on why he was out so late and why he was acting suspicious, Kokichi, being Kokichi, playfully dodged all of her questions, which then resulted in Kirumi lecturing him on his behavior and relationships like a mother would. Kokichi eventually got bored and attempted to leave without saying anything, causing Kirumi to scold him, telling him they weren't finished yet. Kokichi said that "a supreme leader doesn't have to listen to [her]", then laughing and calling her "Miss Mage", and then ending his teasing with a "catch me if you can". Kirumi, being the Ultimate Maid, took this request incredibly seriously and proceeded to chase the Supreme Leader around the school, until eventually catching him and lecturing him again, causing him to be an hour late to the insect meet-and-greet that he convinced Gonta to host. During the class trial, Kokichi proved Kirumi's innocence by telling everyone proof that she was only in the gym for five minutes. Kirumi, annoyed, told him that the information could have been said beforehand, but Kokichi claimed that he "totally didn't hide the information on purpose to make the class trial interesting".
After Kirumi had been proven as Ryoma's murderer, Kokichi seemed disappointed, yet not surprised. Kirumi began confessing her motive for murder, which were the contents of her motive video given to her by the Monokubs. She explained that she was the prime minister of Japan and that she was so heavily devoted to her people and her country, that she had to sacrifice the rest of the students in order to run her country again. All of the students seemed moved by her devotion, some even offering to sacrifice themselves and let Kirumi escape, yet Kokichi saw through her lies and called her out for using her motive video to garner pity. Kirumi was enraged by this, snapping at him and calling him "the most detestable cretin [she] has ever met."
After her execution, Kokichi cried his usual over dramatic tears and sobbed about Kirumi's cruel and violent death. But his waterworks stopped and he gave the rest of the horrified students a genuine and/or neutral smile, stating that running away in order to live isn't a bad thing, implying that he may still have some respect for Kirumi despite the two's conflict before her death.
In Chapter 3, the day after Kirumi's execution, Kokichi sobbed to Shuichi that he misses "his mom's" cooking, Shuichi replies by asking Kokichi if he knew that Kirumi wasn't actually his mother, to which Kokichi says he knew.
Most fan arts of the two together often display Kokichi acting like a bratty child with Kirumi playing the tired mother role, and some fanfictions contain them acting like mother and son together, as well.
There are some people who ship the duo romantically, but this is rare as Kokichi has some more popular ships such as Oumasai, Oumami, Oumatsu, Oumeno, Irouma and Kiibouma, and Kirumi also has some more popular ships such as Kirukaede, Kirumaki, Kirukiyo, Amojo and Tojoshi.
- In the official art book, it is indicated that Kirumi regularly polished Kokichi's shoes.
- They can be seen placed next to each other during the Danganronpa V3: Killing Harmony Opening at 1:28.