Bornea was stopped by Takuma Inoue in the eighth round of a scheduled 10-round contest.
Referee Katsuhiko waved off the bout in the 2:48 mark after suffering a huge gash on his left eyebrow.
Takuma, the brother of Naoya, overwhelmed Bornea with his swarming combinations. Bornea suffered a cut in the seventh round and it worsened in the following round which caused the stoppage.
Bornea dropped to 14-4-1 with seven knockouts, while Takuma, a one-time world title challenger, improved to 17-1 with four knockouts.
On the other hand, battle-scarred veteran Leon was stopped by Satoshi Shimizu in the second round.
Leon quit on his stool and didn’t answer the third round.
Leon fell to 14-23-5 with six knockouts, while Shimizu is now 11-1 with 10 knockouts.
In the main event, Naoya (24-0, 21 KOs) totally dominated Butler (34-3, 15 KOs) and knocked him out in the 11th round.
Naoya is now a unified bantamweight champion. /