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.

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