How to Get Mutations in Steal An Egg On KuKirin

In Steal An Egg On KuKirin, mutations come from hatching. The game's Hatch pets (ペットを孵化) feature has you hatch the eggs you've collected (集めた卵) to gather rare pets, and it lists pets, sizes, mutations (突然変異), and more as the discoveries waiting in that activity. That makes hatching collected eggs the one documented game event that can hand you a mutation. What it does not document is anything else: no other mutation source, no odds, and no on-screen sign that confirms you got one. This page covers the route that is on record — and is upfront about the part nobody has documented yet.

The documented route: collect eggs, then hatch them

1. Come out of an egg run with eggs in hand. The hatch instruction starts from "the eggs you collected," so hatching works on eggs you've already gathered on your runs. The collection loop itself — sneaking in, grabbing an egg, getting out — is covered in how to steal eggs.
2. Hatch them under "Hatch pets". This is the event where mutations can surface. A hatch can turn up a pet, a size, a mutation, or another discovery the feature advertises. For hatching mechanics in general, see how to hatch eggs.
3. Keep the loop going. Because mutations appear inside hatching rather than through any separate documented system, repeating the collect-and-hatch cycle is the only evidence-backed way to keep pursuing them. What the game's description doesn't give you is a rate — there is no documented way to know how often mutations show up per hatch.

How you know you actually got one

The honest answer: the game's own description doesn't say. It names mutations among the things hatching lets you discover, but it describes no label, tag, trait line, collection index, pop-up, or result screen that confirms a mutation — so there is no confirmation step this guide can describe in good faith. The reveal is framed as part of the hatch loop itself ("you discover" pets, sizes, and mutations by hatching), but where exactly the result is displayed is undocumented. Treat any guide that names a specific marker or menu as adding something the game's text doesn't put on record. And note the distinction: an undocumented sign is not proof that no sign exists — only that nobody has described one yet.

What the documentation leaves open

• Odds and guarantees. No drop rates, hatch counts, or "hatch N eggs" rules are documented, and nothing says a mutation can be bought or otherwise guaranteed.
• A second source. Shops, events, and other systems are not documented mutation sources — hatching collected eggs is the only one on record.
• What a mutation looks like. Whether a mutation is a trait shown on the pet, something tied to size, or a separate collectible entry isn't documented.
• The hatch interface. Where the hatch action sits in the game's menus isn't covered by the feature description either.

The practical takeaway

If you want to chase a mutation today, the evidence-backed route is the hatch loop itself: run for eggs, hatch everything you've collected under Hatch pets, and pay attention to what each hatch turns up. That's the entire documented path — everything past it, from odds to confirmation signs, is still unrecorded. New to the game? Start with how to play, then take the full egg run guide into your next run.