Day of the Battle is the 167th episode of the Katekyo Hitman Reborn! anime.
As the Six Funeral Wreaths prepare for battle, Tsuna visits Lal Mirch to tell her to rest as well as to tell her to not come. Afterwards, everyone puts on special mafia suits made from Leon's thread, which is immune to Dying Will Flames. They arrive at Namimori Shrine, where Shoichi Irie has prepared a base of operations. However, Yamamoto and Hibari have yet to arrive. Byakuran appears, telling them they'll need to provide a massive amount of Dying Will flame energy to activate a teleporter to take them to the battlefield. Yamamoto and Hibari arrive at the last minute, and, with their Vongola Box Weapons, the group manage to produce double the power needed.