Per-overlay catalog

Tongari Boushi's code is split into 180 ARM9 overlays — small chunks of compiled ARM code that the DS swaps into a shared RAM slot as the player moves between game modes. Each overlay handles one screen, one feature, or one engine subsystem. This catalog is the per-overlay field guide: one page per overlay, describing what it does at runtime, what container files it pulls from disk, which UTF-16 LE strings are baked into its own binary, and the function table Ghidra's auto-analysis pass found inside it.

The overlay system page covers the runtime mechanics (RAM slot map, the controller/body pattern, the persistent rendering engine in ov137). The overlay knowledgebase page is the plain-English "what's an overlay?" explainer. This page is the searchable per-overlay index.

How the catalog reads

• Overlay — the ROM ID (ov000 through ov179). Click through to the per-overlay page.
• Purpose — a one-line summary drawn from the container files the overlay references. The small pill is the prior-pass role guess (the rough "what is this for" tag we had before the deep Ghidra pass).
• Fns — function count Ghidra auto-identified. Many are small trampolines; the dispatcher and high-fan-out functions are the meaty ones.
• JP strings — UTF-16 LE strings baked into the overlay's own binary. These live inside the compiled code section itself, not in an external container file.
• Containers — distinct container basenames (looking like buyitem.lzs, chest.lzs) the overlay references by string. These are the disk-side data files the overlay loads at runtime.

What's an overlay made of

Each overlay is a self-contained ARM module with five rough contents:

• Code — ARM/THUMB functions. Most overlays are almost-entirely code; the actual translatable text lives in container files loaded at runtime.
• Data tables — fixed-stride sprite-placement tables, dispatch tables, type tables. Read-only at runtime.
• Container references — ASCII strings naming .lzs, .ofs, .nftr files the overlay's loader calls into the content cache for. The string is passed to a lookup that resolves it to a file ID in the ROM's FAT.
• Embedded UTF-16 LE strings — direct text, baked into the overlay binary itself rather than loaded from a container. These are typically short menu labels and confirm prompts.
• External call targets — addresses in the persistent ARM9 binary the overlay branches into for shared helpers (memory management, OAM transfer, content cache lookups).

RAM-slot map at a glance

Overlays sharing a RAM address are mutually exclusive — only one is resident at a time. The dispatcher in the persistent ARM9 binary chooses which overlay to load into each slot based on game-mode state.

Functional groupings

Inferred from substring-keyword matches on container filenames plus the deep Ghidra pass. Boundaries are approximate.

• 2D UI screens — ov000–ov065 (game-mode controllers) and the slot-1/2/3 body renderers behind them. Shops, menus, chat panels.
• UCC / dress-up — ov108, ov141, ov148–ov155. Outfit-composition surface.
• Map / world — ov080, ov115–ov117, ov127, ov138, ov156. Field navigation, world map.
• Persistent engines — ov137 (2D rendering), ov138 (3D map engine). Co-located at 0x0216da40; one resident at a time.
• Audio / system — ov132–ov136.
• Pure code / dispatch — many of ov018–ov024, ov094–ov099, ov102–ov107, ov128–ov136, ov160–ov179 have no embedded strings and no container references; they are pure logic.

Per-overlay catalog

Source

• notes/_overlay_knowledgebase.md — high-level overlay survey.
• notes/_overlay_knowledgebase.csv — flat CSV of the same.
• notes/overlay_knowledgebase/ov<NN>.md — one descriptive markdown per overlay.
• notes/overlay_knowledgebase/raw/ov<NN>.json — raw Ghidra dump per overlay.
• notes/phaseA_ghidra/overlay_role_final.json — per-overlay role classification.
• notes/phaseA_ghidra/container_to_overlay.json — reverse map: container basename → overlays referencing it.
• notes/phaseA_ghidra/overlay_string_inventory.json — every overlay-embedded string with offset and encoding.
• notes/phaseA_ghidra/DISCOVERIES.md — aggregated reverse-engineering log.