In 2021, Okubo Nalu participated in the second season of the Japanese version of the reality competition show Produce 101 Japan 2. For his promotional vocal video, he chose the song "Sayonara Elegy" (さよならエレジー) by Suda Masaki. He auditioned in the audition group DK WEST *. He received an evaluation grade of C and dropped to D after his re-evaluation. During the group battle, he was in the group Ababies (アベイビーズ) and placed 1st within the group. He ranked 12th in the final episode.