Yamakatsu

 was an idol group based in Yamaguchi. They were originally named Yamaguchi Kassei Gakuen (山口活性学園) and were very often nicknamed Yamakatsu (山活), but changed their name in April 2018.

Previously, members were split into the Idol and Artist departments, which eventually merged. They were also split into Stamen and Submen. Submen was named 30POSSE in June 2013, and, while still considered the under-group of Yamakatsu, performed separately as their own unit.

On December 29, 2022, it was announced that the group would disband after a final live on April 2, 2023.

Final Line-Up

 * Yuly
 * Tsuneoka Moi (常岡もい)
 * Moriwaki Yui (モリワキユイ) (Joined March 20, 2012)

Former Members

 * Ajimura Yui (味村唯) - Submen (Graduated June 16, 2012)
 * Kanno Meyu (菅野明優) - Submen (Graduated July 18, 2012)
 * Nakatani Yoshino (中谷淑乃) (Graduated August 26, 2012)
 * Miyamoto Maria (宮本まりあ) - Submen (Became a 30POSSE Member June 2013)
 * Fujii Misaki (藤井海咲) - Submen (Became a 30POSSE Member June 2013)
 * Miyata Ayaka (宮田綾華) - Submen (Became a 30POSSE Member June 2013)
 * Harada Amane (原田海希) - Submen (Became a 30POSSE Member June 2013)
 * Oda Manaka (小田愛花) - Submen (Became a 30POSSE Member June 2013)
 * Matsuo Haruka (松尾遥香) - Submen (Became a 30POSSE Member June 2013)
 * KRISTINA (Left Unknown)
 * Okamura Momoka (岡村百華) (Left April 2017)
 * Yamatsuka Haruno (山塚はるの) (Left April 2017)
 * Mugi (むぎ) (Left December 31, 2021)
 * Fujii Rena (藤井澪奈) (Left December 31, 2021)

Albums

 * [2013.08.07] NOTE
 * [2015.04.22] NOTE2
 * [2017.01.31] NOTE3
 * [2017.07.25] NOTE4
 * [2020.02.04] NOTE5

Singles

 * [2012.05.30] HELLO MY NAME IS
 * [2013.01.30] RUN!!
 * [2013.06.26] STEP×STEP
 * [2014.02.19] IDREAM
 * [2014.08.20] Ignition (イグニッション)
 * [2015.07.28] PARADOX
 * [2016.05.31] ONE
 * [2018.04.17] distopia
 * [2018.11.20] STAY GOLD

Digital Singles

 * [2016.09.21] Shakunetsu (シャクネツ)
 * [2019.04.06] Phenix