Neon Genesis Evangelion v.10

Ayanami, who was supposed to have disappeared with the apostles to protect Shinji, is still alive? What does Ayanami mean when she says "the third person" to Shinji's happy face? ......

Ayanami, who was supposed to have disappeared with the apostles to protect Shinji, is still alive? What does Ayanami mean when she says "the third person" to Shinji's happy face? ......