A Reason to Fight is the 46th episode of the Katekyo Hitman Reborn! anime.
After Belphegor reveals his true nature, Gokudera lures Belphegor into the library for a final standoff. After a brief struggle between the two, Gokudera won, but as the time limit for the match expired, it became a struggle match for the two. Not wanting to lose his friend, Tsuna persuaded Gokudera to abandon the ring. The match concludes and Belphegor emerges the victor.