One type of character that’s quite common in anime is osana-najimi or childhood friend, who grew up alongside the main character and knows everything about him. But an osana-najimi isn’t exactly a friend, it’s both more and less. “It’s like they’ve always been there, and you never think about them. Since you were together from the beginning, you can’t remember a time when that person wasn’t around.” In anime, characters like Mayuri in Steins;Gate, Kanna from AnoNatsu, Eriri from Saekano and Houki from Infinite Stratos all have this special relationship with the main character, which is both an advantage (they have information other competing girls don’t have), but also a problem (since they’re so familiar it’s hard for the main character to view them romantically). Childhood friends are a fixture in eroge too, including a favorite of ours, My Childhood Friend is the President.