Talk:Underground Treasure Chest 4/@comment-27924355-20160413132953/@comment-27584537-20160414043848

In some previous events, koban was used to get passes that grants you passes to enter the event front lines. Maybe you can check the details of previous events to find out more.

http://touken-ranbu.wikia.com/wiki/Regiment_Battle --> in the general section, it mentions the use of koban