(Old Japanese. It was used in various situation ,various meaning. For example, it could be used instead of "hello" "Anyone home?" "Good bye" at the entrance hall. It also worked as an expression of one's courtesy, it ment "Excuse me "and "Pardon." It was used to make the other pay an attention before he did something (as a shock absorber in the dialogue ). In this case , Bishamon uses this word as a previous announcement to kill the oponent.