Wait, there are people who didn't guess as soon as she mentioned her older brother? This must be your first manga, huh.
Also, Toramaru now almost comes across as being attracted to Unoki because he fills the hole her younger brother left in her life when he stopped needing to be protected. Like she wants to bone the version of her bro who was a cute little shota. Which would have been way hotter, but this is fine too I guess.