Shokei Shoujo no Ikiru Michi - Vol. 3 Ch. 14 - Across Time

[MangaDex]

 

[Coldlight]

This is a pretty big reveal for Akari. Her future self can interfere and take over? It's unsurprising that stopping time becomes part of her suite of time-based powers, but that fluid thing derived from a Pure Concept being unaffected by it is.

Also, yeah, that's more than just mean, that really is a bitch move on Future!?Akari's part.