Shiori is referring to Roto's brother here, who was stalking her while Roto was fighting Kurama. If Hiei hadn't confirmed that such a being existed (in the dub, he says that Roto's brother vanished when Roto died), I would never have believed it. I always thought it was just a bluff.
Dearest Shuichi
5. All the Happiness I Need
Dearest Shuichi—
Your excuse is a little thin, but I won't press you on it. It isn't often that you ask to leave for an entire week, and you've promised to call and let me know you're all right, so I don't see that I really have a choice. I'm afraid that if I tell you no, you'll go anyway and then you definitely won't come back. You're going with friends, and that's good. You have good friends. I've been feeling a little watched lately—like something's following me, though I'm not sure what. You're distracted and busy, so you don't notice. You've been on edge lately. My hope is that you'll come back in a week and feel better. I pray for that, son, because you are all the happiness I need. Someday you'll understand that.
Signed,
Your mother.
