A few fun facts:

• R.ei has 3 of those orbs that are hidden within her hair
• R.ei doesn’t require a powersuit [for the same reason Tsuna Mei doesn’t require one either: they’re both a bit OP]
• R.ei is a stylized name for Retro Mei, keeping the /mā/ consistent in each of the 5 girls’ names (Annie Mei, Megan, May Gunn, Retro Mei, Tsuna Mei)