Fiesta For The Observers I (観測者たちの宴篇I Kansokusha-tachi no Utage Hen Ichi) is the sixteenth episode of the Strike the Blood anime.
Kojou comes out of the battle with his own body back, but both Yuuma and Natsuki have fallen. The true prison barrier has been revealed along with Yuuma's mother, Aya Tokoyogi, and the other magic criminals who were incarcerated within.Kojou escapes with Yukina and injured yuuma with the help of Sayaka.They head to meet Kojous mother to heal Yuuma.
- Le Ombre.
- 12th Familiar - Pisces Dodekatos, Alrescha-Glacies.