Saki Fujiwara is friends with Sakura Asakura. When Sakura confessed to Kou Yamori and got rejected, Saki took it upon herself—along with Michiko—to harass Kou about it, even though Sakura never asked them to. It's a pretty typical move for her, honestly. Saki tends to be impulsive and doesn't always think about how her actions affect people.
She's got a weakness for good-looking guys; the other girls have definitely noticed that Haruka's type is exactly her thing. When it comes to reading the room, though, she can be pretty insensitive and often says or does whatever comes to mind without filtering it first.
Content compiled by AnimeList.moe from publicly available sources.