Psyllium no Shoumei

 is the 21st single released by Houkago Princess, and the second single to use their own Princess theme.

Tracklist

 * 1) Psyllium no Shoumei (サイリウムの証明 )
 * 2) Mukai kaze o Tsukinukute (向かい風を突き抜けて)
 * 3) Psyllium no Shoumei (Instrumental)
 * 4) Mukai kaze o Tsukinukute (Instrumental)

Featured Members

 * Sekine Sasara
 * Michishige Saho
 * Kohinata Nanase
 * Sawada Momoka
 * Nishimiya Airi (Debut single)
 * Nakano Rion (Cadet)
 * Morikawa Yuu (Cadet)
 * Mizuno Ami (Cadet)
 * Yoshioka Maki (Cadet)

Single Information
Psyllium no Shoumei tackles the groups second original Princess concept, 'Princesses of the Idol world' to celebrate the 10th Anniversary of Houkago Princess. A feature of the title tracks choreography is that the members use penlights in their member colours, reflecting how their fans will use penlights during the groups live performances.

This is also the first single since 2014 that does not feature former member, Miyashita Maika. It is also one of the first singles since to include the members of Houpri Youth in more than the chorus for songs.