[The whole time Kizakura's going through the riddle, Mahiro just watches on silently. He doesn't show much of a reaction when Kizakura explains his reasoning, although he will nod at the end.]

So you caught on to the significance of those letters too, huh. He was pretty transparent about it.

[...]

I think you missed a couple, though.

[He'll go back to the sheet and underline, like so:

don't be the new third boy, kk? KK.]

Does that look important to you? Kizakura Koichi.