Akechi Mitsuhide is a playable character that has appeared in Sengoku BASARA and Sengoku BASARA 2. He is an Oda vassal, that eventually ends up betraying his former master.
Mitsuhide is depicted as a psychopath that enjoys the suffering of other people; possibly of a greater evil than Oda Nobunaga himself. This is depicted as he is one of two characters who can hurt his allies, though they don't lose life. Wields dual scythe.
Mitsuhide is reportedly slain by Toyotomi Hideyoshi after his betrayal of Nobunaga. He is featured in Sengoku BASARA 3, in disguise, under the name of Tenkai.
Tenkai is a non-playable character in Sengoku BASARA 3 and one of the several NPC's to become playable in Sengoku BASARA 3 Utage. He is a high-ranking monk standing at Kobayakawa's side. With sweet words and turns of phrases he guides the indecisive Kobayakawa as he wants. No one knows his true identity, though he bears an uncanny resemblance to Akechi Mitsuhide. However, in Sengoku BASARA 3 Utage, his true identity was eventually revealed to be Akechi Mitsuhide in disguise, showing that he survived from Hideyoshi's attack.
In Oichi's Green Route, he claims to want to ressurect Lord Nobunaga and fight him for some undiscernable reason. Should you defeat him, he will claim that "The Enemy Is At Honnoji". Following this, Oichi will go to Honnoji, and Tenkai will die anticlimactically at Nobunaga's hands. They seemed to know each other, as Nobunaga calls him "still" a fool which is ironic because in Nobunaga's ending Nobunaga says that he doesn't know him much to Tenkai's horror, however Nobunaga's claim that he "does not know" Tenkai could simply be a refusal to acknowledge Tenkai's achievements to keep Tenkai from dying in peace.
In several character's stories, when defeated before or during Sekigahara, he kills himself. He closes his eyes and speaks of peace at the edge of a sea cliff before letting himself fall from the cliff into the water, thus dying.
Tenkai is also unlockable as an ally, by defeating him using Oda Nobunaga. As an ally, he has a special ability: Evil Eyes, that will make enemies panic when stared by him.
And he is reprised by Vic Mignogna in the English dub and Sho Hayami in the Japanese dub.