Another critical week for Prime Minister Yoshiro Mori began Monday with the Upper House approving the resignation of Masakuni Murakami, one of the embattled prime minister's staunch backers.

Murakami, formerly dubbed the Liberal Democratic Party's Upper House "guru," had his resignation unanimously approved at a plenary session in the morning.

Murakami submitted his resignation last week for "causing trouble" through his alleged ties with KSD, a mutual aid foundation at the heart of a widening bribery scandal.