1x39 - Eyeshield 21

While hiding from a group of television interviewers, Suzuna questions why Sena doesn't tell Mamori who he is. This leads to a quick review of the previous 38 episodes. In Japan this aired as an hour-long special with 40. Sena tells Suzuna that he will tell Mamori his identity when he is truly strong, namely when he defeats his ultimate rival, Shin Seijuuro.