I remember getting that far about a year ago. Obviously, I haven't progressed.
I... I am ...the breast!
Both the usual 最強 (strongest) and 最胸 are pronounced 'saikyou'.*blush*'~teba' -> '~tara'
Cirno's catchphrase "I'm the strongest!" is あたいったら最強ね! "Ataittara saikyou ne!" However, it is a common mistake to write あたいってば最強ね! "Ataitteba saikyou ne!" instead.