Thomas is a Koala that was put in the Alcamone prison for unknown reasons. He enjoys bullying other inmates at the prison. He claims to have been known as Eucalyptus Thomas before he was put in Alcamone.
Appearances in the anime
When Don is put into Prison Alcamone, he quickly realises that his new friend Akiyoshi was being bullied by Thomas. However Don doesn't do anything directly towards Thomas until he realises that Thomas is the rat that betrays Akiyoshi when he gives the library book that Don had chewed on to one of the security guards, who assumed that it was Akiyoshi who had done it. Don then proceeds to challenge Thomas to a fight. Neither of them win the fight because they are interupted by Akiyoshi who transforms into a werewolf. After a short argument between the forces of NORA and the mafia (who had come there to free Don), Akiyoshi jumps onto Thomas which scares Thomas considerably. Akiyoshi doesn't kill Thomas, so in repayment for his great dead, Thomas decides to be Akiyoshi's minion and help him out.