To get Insect Breathing in Weak Legacy 2 , you need to meet a level and money requirement, then talk to the Insect trainer NPC and complete a short demon‑killing quest.

Basic requirements

  • Be at least level 15 on your character before you try to learn Insect Breathing.
  • Have around 10,000–100,000 Yen ready (some guides mention 10k, others 100k depending on update, so expect a high Yen cost and check your version).

Finding the Insect trainer

  • Go to the Demon Slayer / Demon Slayer Corps area (sometimes called Demon Slayer Village in guides).
  • The Insect trainer/Shinobu‑style NPC is located inside this Slayer area; you reach her by traveling from the starter village into the main Slayer base and looking for the insect‑themed trainer building or room.

Unlocking Insect Breathing

  • Talk to the Insect trainer once you meet the level and Yen requirements.
  • Accept the quest to defeat about 25 low‑level demons or grunt demons; this is the standard requirement shown in multiple guides.
  • After killing the required number of demons, return to the trainer to turn in the quest and you will unlock Insect Breathing as your breathing style.

Note on rework and modes

  • In later updates (Insect Breathing rework), you can further unlock Bee, Butterfly, and Horsefly modes, but these come after you already have Insect Breathing and usually require high breathing level, more Yen, Demon Horns, and boss kills.

If your game version doesn’t match the numbers exactly, follow the same pattern: reach the Slayer area, find the Insect trainer, pay the Yen fee, then complete the demon‑kill quest to learn Insect Breathing.

Information gathered from public forums or data available on the internet and portrayed here.