Orbital Period is the fifth studio album by Bump of Chicken, released on December 19, 2007. The album features the singles "Planetarium", "Supernova/Karma", "Namida no Furusato", "Hana no Na", and "Mayday". Orbital period became the best-selling album two days in a row at debut, according to Oricon Style. It was the second best-selling album on its debut week.