The Sure-Death Device -- Three-cornered Blood Match!

Waruda and Bjinda start sending each other letters. Waruda wants to learn to be good and Bijinda tries to teach him. The Shadow takes over a post office in order to send forged letters causing loved ones to hate each other, turning friends into enemies. When Hakaida discovers Bijinda and Waruda are exchanging letters he sees it as an opportunity to set a trap and send...