Zekū (是空) is the third studio album released by Mucc on September 3, 2003. The first press limited edition release included a DVD, different artwork, and a bonus one track CD. The European version, released on May 19, 2006, features two bonus tracks which were b-sides from the single "Waga, Arubeki Basho".[1] The album reached number 17 on the Oricon chart.[2]