Between 2001 and 2002, with the release of the single "Another World", Gackt began another concept called "Moon". There were two nationwide tours represeting his new concept, a live house tour, prior the release of his third studio album Moon on June 16, and a second started on October 14, known as Kagen no Tsuki (下弦の月?, The Waning Moon). On September 22, he appeared in a large musical event called "China-Japan: Holding Hands, Moving Together" at the Beijing Worker's Gymnasium, in China. The event was part of a "Japan-China Diplomatic Relations Normalization 30th Anniversary Commemoration".
In 2003 Gackt announced his film Moon Child. He worked on the script, and did own action scenes on location in Taiwan. In collaboration with co-star Hyde, he also sang the film's theme song "Orange no Taiyō" (オレンジの太陽 Orenji no Taiyō, "The Orange Sun"). Film was released on April 19 in Japan, and screened on May 13 at the Cannes Film Festival and on April 12, 2004 at Philadelphia Film Festival.On May 5 launched his nationwide tour Jōgen no Tsuki (上弦の月, The Waxing Moon), continuing the concept of the previous one On August 6, Gackt released "Gekkou" featuring video clips from previous singles "Kimi ga Oikaketa Yume" and "Tsuki no Uta".
On September 27, Gackt performed as a special guest at the TV Asahi 45 anniversary commemorative "Kingdom Rock Show".On October 2, he performed the John Lennon song "Love" in acoustic and rock versions at the "Dream Power: John Lennon Super Live" concert held in Saitama Super Arena. Through November and December, he released his sixteenth single "Last Song", and his fourth concept album Crescent. Also in 2003, Gackt published a novel Moon Child Requiem, and his autobiography, Jihaku, and performed on the 54thKōhaku Uta Gassen performing "Last Song".