Chihiro and Gundham haven't canonically met, since they are from different games. In their own game, Chihiro once mentioned that he wanted a pet hamster, which led to thinking about interactions between the two, since Gundham owns a lot of hamsters. Later, in the Ultimate Talent Development Plan, Chihiro and Gundham have a couple of interactions that hint to a friendship between the two.
In one of their interactions, he states that Chihiro is purehearted, so he can touch his Four Dark Devas of Destruction without problem, and then warns him that they are still demon beasts, which Chihiro understands what he means, and that doesn't happen often because of Gundham's speech patterns. Later in the game, Gundham's class decided to throw a Christmas party, and after it ended, he was in charge of throwing away the trash. Chihiro then appears, saying he got so caught up in his research that he forgot to eat, and Gundham offers to share the food from the party with him.
In one interaction with Kaede and Maki, Chihiro was crying because he had found an injured bird, but it died before he could do something to help. After some talking, Chihiro says he wanted to bury the bird, and Maki suggests that he should go talk to Gundham about that.
They even have one official art of Gundham, Chihiro and Monomi with the Dark Devas.
Ultimate Talent Development Plan
"Perhaps one as purehearted as you may be able to touch the Four Dark Devas unscathed."
— Gundham, saying he found Chihiro to be purehearted.
"However, should you seek food, then journey beyond this place.
You may be able to consume the excess offerings from the rite of chaos."
"Offerings such as birds grilled in hellfire and ensorcelled confections.
No one will blame you for being lured to such offerings... Go and eat."
— Gundham, saying he wants to share the food from the party with Chihiro.
The ship is not very popular, since both of these characters have more popular ships with other characters, such as SonDam, SouDam and ChiMondo, plus that pairings from different games aren't very popular for the lack of content.
Fans of this ship like it because of the opposite personalities these characters display, with Gundham being extra and edgy, while Chihiro is low profile and sweet.
- Chihiro seems to have little to no trouble understanding Gundham's speech patterns
- Such a thing is rare even between Gundham's classmates, who usually don't understand what he means