The phrase "collecting all the 'aya'" means accumulating a great deal of power or influence. In this context, it refers to Aritsune's possession of the powerful "Kaiyori no Aya," which makes him a target for rival houses seeking to acquire his abilities.
Aritsune is an intelligent and athletic high school student who lives with his sister Akira and friend Chihiro. He also heads the Sagimori House, where he wields the "Kaiyori no Aya," granting him significant power. However, this makes him a target for other houses seeking to acquire his abilities.
As a result of his position, Aritsune occasionally receives orders from his house to deal with rogue collectors who disregard others in their pursuit of power. Chihiro supports and helps Aritsune control his abilities during these missions. Despite the challenges they face, they maintain a peaceful school life until violent crimes increase and suspicious transfer students arrive.
Given this context, it is crucial for Aritsune to determine whom he can trust as he navigates through these challenges.