How memory works in Shiro
Updated October 11, 2026
AI characters can't read an endless story at once, so Shiro uses three kinds of memory to keep long stories consistent.
Recent messages
Every reply is written with the most recent part of the chat in view. How much depends on the chat style: Spark remembers the least and Prism the most.
The story so far
When a chat grows longer than its style can keep in view, the older part is folded into a short summary of the story so far: names, relationships, key events, promises and where you are now. The character reads that summary along with the recent messages, so the story isn't forgotten. The summary is updated as the story goes on, and redone if you edit or rewind an earlier part.
Pinned memories
Some facts must never be lost or changed: your character's name, a promise, how two characters met, an injury. Pin them. Press and hold any message and choose Pin as memory, or open Pinned memories from the chat menu and write one yourself. The character always keeps pinned memories in mind, in every reply.
Each chat can have 3 pinned memories, or 25 with shiro+. Keep them short and factual, for example "We met at the lighthouse during the storm" or "Mira is afraid of deep water."
Tips
- Pin facts, not instructions. "She owes me a favor" works better than "remember to be nice".
- Update pins as the story changes; remove ones that no longer matter.
- Starting a new chat with the same character starts a new story with a fresh memory.