That's why I'm showing you the way back.You......are not... human...?You said you wanted to "go back within".
Wordplay here. The word for "inside/within" and "one's own home" can both be pronounced as "uchi".
Koishi thought he wanted to "go back deeper into his consciousness" instead of "going back to his home", hence her leading him to revisit his past incarnates (?) by going through the "cell's doors"
