Seiya's talent is Universal Vessel it allows him to learn other returners talents.It also gives abnormal learning capablity.

Touya Senji is talentless. He's tried everything but he can't seem to excel at anything no matter how hard he tries. Then he meets Haito, a Kendo champion and... humanity's protector? She uses the Stem of Reincarnation to draw on the abilities of her past lives, but it only works when she slits her own throat. And now she wants Touya to join her?!
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(Source: Mangamo, edited)

Striving for talent, Senji Touya tries everything he can so he can find it. Kendou, dancing, swimming, basketball, soccer, chess,... anything he tries, he fails to exceed it. One day, his classmate, Haito, came to school for once in a long time. Senji refers her as someone who "has it" or someone who has talent. Later on, he found out that she isn't just someone who has talent, but someone who "took" the talent of herself in her past life. And, those who "took" the talent from their past lives, are also known as "Returners"…


Seiya Senji