>>283277003
Tooe was a prodigy among prodigies. She was so ridiculously talented that they literally added an entire field of supernatural studies to Kyoto University (I think it was) for the sole purpose of cultivating her talent. But she impulsively ran away to get married in high school, before she even set foot in college. As of Tsugimonogatari, she's been gone for seven years and it sounds like she died a week or two. The other characters are in their early 20s, save for Kagenui. So I THINK Tooe ran off around 16 and died around 23. But it's very possible I got something wrong somewhere.
But Tooe's role in the story is interesting, because nobody's seen her in forever, so she's like this mysterious presence looming over the story. The characters always talk like they're just speculating about her, since they really have no idea what she's been up to. Oshino didn't even know her married name until the events of this book. (Kaiki did, but refused to ever speak it)