4th Ikimasshoi! (4th 「いきまっしょい!」^?, 4th "Let's go!") is the fourth album from the J-pop idol group Morning Musume and was released on March 27, 2002.

It is currently their second highest selling album, with a total of 515,400 copies sold. Since their last album (with new material) 3rd: Love Paradise, two more generations of members had joined, which might have contributed to the album's overall success. The album contained such popular singles as "The Peace!" and "Ren'ai Revolution 21." The first pressing edition of the album came in special packaging, with a B3-sized folded poster.

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