Even though both characters are from the same instalment in the series. Chihiro and Hifumi do not share any significant interactions with each other throughout Danganronpa: Trigger Happy Havoc. Despite this, the two appeared to be on good terms, and are never shown to hold any resentment towards each other.
In Chapter 2, Hifumi expressed sorrow over the death of Chihiro. Before the trial, Hifumi says that despite being 3D, he found Chihiro to be quite remarkable. However, he still firmly insists that the thought of 3D makes him cringe. With this exception, it can be inferred that Hifumi was attracted to Chihiro, although it should be noted that he was still under the assumption that they were female. He later reacts in horror upon finding out that Chihiro was actually a boy.
During Chapter 3, Hifumi develops romantic feelings for an artificial-intelligence named Alter Ego, describing them as the first "girl" who he felt comfortable being around. The AI was created by Chihiro, and was designed to perfectly mimic the appearance and actions of anyone else. Because the version of Alter Ego that Hifumi interacted with resembled its creator, Chihiro, this further indicates that he may have had feelings for the programmer, but did not pursue them because of his commitment to 2D.
During one event in Ultimate Talent Development Plan, Chihiro finds Hifumi celebrating in the cafeteria, and asks him if something good happened. Hifumi tells him that he had just finished the manuscript for his latest fan comic, and was really proud with how it came out. Chihiro congratulates him and says that he makes many people happy with his comics, and starts to ponder about something. Hifumi wonders if Chihiro is going through a tough time, and asks if he can recommend some anime songs to cheer them up. Chihiro then asks Hifumi if it would make him happy if he could talk to people from inside of a screen. Hifumi is surprised, as he never expected to hear something like that from Chihiro. He then says that it would make him happy, as it was every otaku's dream to talk with 2D. Chihiro tells him about a project that he is working on where this can be achieved, although his explanation confuses Hifumi. Chihiro clarifies things a little better, and Hifumi says that people would enjoy it. Chihiro tells him that once his project is completed, he would like for Hifumi to talk to it, and Hifumi says he'll be looking forward to that day.
- “Miss Fujisaki... I must admit, for being 3D, she was quite remarkable.”
- — Hifumi admitting that he found Chihiro to be remarkable.
The ship was likely the result of both characters embodying a variation of the "nerd" archetype, with Chihiro being the Ultimate Programmer, and Hifumi being the Ultimate Fanfic Creator. Hifumi's romantic attraction to Alter Ego was also likely a contributor, because Hifumi fell in love with a nearly exact replica of Chihiro, except in his preferred 2D format.
Prior to Danganronpa 3: The End of Hope's Peak High School, some fans speculated that Hifumi may have helped Chihiro with the design of Chiaki Nanami, who was revealed to be another AI that the programmer created. However, this theory was debunked with the reveal that Chiaki was actually based on a real-life student who also attended Hope's Peak Academy.
- Both were victims of the Killing School Life in back-to-back chapters. They were seemingly back-to-back victims at first, until the reveal that Hifumi had murdered Kiyotaka Ishimaru before he himself was betrayed and murdered by his accomplice, Celestia Ludenberg.
- Their cause of death was also the same, as they were both bludgeoned by a blunt object.
- Class 78th refers to the ship between the two and the other students of Class 78th.