The reason why いきものがかり (Ikimono Gakari) is now a 2-person unit is because one of the original three members, 山下穂尊 (Hozon Yamasita), left the group in 2021. The group was originally a trio consisting of 吉岡聖恵 (Kiyoe Yoshioka) as the vocalist, 水野良樹 (Yoshiki Mizuno) on guitar, and 山下穂尊 as a guitarist. After many years of activity since its founding in 1999, and a period of hiatus, 山下穂尊 decided to leave the group to pursue new creative activities and personal paths. Since then, いきものがかり has continued as a duo with 吉岡聖恵 and 水野良樹. The departure was amicable and occurred after discussions reflecting their evolving feelings towards the band, accentuated by the impacts of the COVID-19 pandemic and personal circumstances.