Ima Suki ni Naru.-triangle story- is the "-another story-" song of Ima Suki ni Naru., from the perspective of Kotaro Enomoto. It focuses on his pining for Hina Setoguchi while she's busy chasing after Koyuki Ayase. The song first commercially appears on the Haniwa Kyoku Utattemita 5 album, the album it was written for, a day after its internet release.
Being from Kotaro's perspective, we see that he's pined for Hina for quite a while, and is slightly jealous that Hina devotes her time and affection to Koyuki. We also see that he's always trying to be by her side when she needs it, and does want to see her happy, but he cannot bring himself to confess to her just yet. He makes an attempt once while the pair was studying for high school exams, but Hina brushes it off and he makes no other attempts afterwards.
When time returns to the moments after Hina's heart got broken, Kotaro is standing near the school gates, waiting for her so that they can go home together.
This is one of the few named "-another story-" perspective songs with a different name, the others being Kinyoubi no Ohayou -love story- and Watashi ga Koi wo Shiru Hi. Like the latter song, it's also one of the few perspective shifting songs that's slower in tempo than the song it's based off of, and uses different instruments.
Although ultimately belonging to the first singer's true love interest like the others, this song is the only "-another story-" that does not come from the original song's other primary focus character.
The Vocaloid version of this song was inducted into Niconico's Vocaloid Hall of Fame.
The cover of HoneyWorks Kyouku Utattemita 5 depicts the hallway scene specifically from this song; the difference there is that Hina is depicted with a string clinging around Kotaro's heart in the image.