In the Mizo tradition, Lusariha or Ravana has seven heads. He is invincible because of a boon from Rama and Khena’s father. However immortality is a gift only meant for the gods and Lusariha is told that that he is safe from everyone, except a small monkey.
Now this is as good as being immortal because monkeys have rarely caused the end of anyone, let alone a seven-headed man fortified by a boon. So Lusariha went about his life without a fear or worry in the world. One day he happened to chance upon Rama and Sita in an intimate embrace. Upon seeing Sita, he is struck by her beauty and immediately covets her.
Lusariha takes the form of a barking deer and appears before Sita, Rama and Khena. Sita wants the deer and sends Rama after him but he dies in his pursuit. When Rama does not return, Sita sends Khena after him. Khena discovers the bones of his dead brother and since he knows magic, he revives Rama. Upon coming back to life, Rama is at first very suspicious of his brother. He accuses him of having illicit relations with Sita and asks him to go through the fire test. Khena comes out of the fire unscathed, thereby proving to his brother that his wife has been faithful and he has not transgressed his role as a brother-in-law.
Meanwhile in the absence of Rama and Khena, Lusariha abducts Sita. And Rama and Khena begin to look for her with the help of their simian friend Hawlaman. However their search is interrupted by Luphirabon (also known as Mahiravan in the some versions of the epic).
Luphirabon carries the brothers away, far away in a land beyond the sea. But he is not able to keep them hidden for too long because Hawlaman comes to their rescue and displaying extreme courage and sharp-wittedness, he takes the brothers back. And then ensues the great battle in which Lusariha is finally brought to his end.
(For more on the Mizoram version of the epic read Rama and Khena)
Story collected by: Arundhuti Dasgupta
Source: The Rama story in Mizo tradition by Lalruanga and Birendranath Dutta; Rama katha in tribal and folk traditions in India