Crane

The Crane Egg is the Epic-rarity egg of the Cherry Blossom, and the pet inside it is Crane. Cherry Blossom is zone 10 of 11 on the normal route; the wiki lists its entry requirement as 2,5B speed, and the nests there are watched by the Oni Tiger.

Base income is $4K/s. Among the 8 pets tagged Cherry Blossom on the wiki that puts Crane at number 8 — Kitsune tops the Cherry Blossom at $1.8B/s. Remember the game multiplies this base by the size roll and by the mutation, so two Cranes can earn very different amounts.

With a colour mutation and no size bonus, the same Crane would earn roughly: Silver ×1.2 ≈ $4.80K/s, Golden ×2.5 ≈ $10K/s, Rainbow ×3.5 ≈ $14K/s (multipliers from the wiki's Mutations page; arithmetic is ours). Add a Giant (×3) or Huge (×5) size roll on top and the numbers multiply again.

Hatching it pays a one-off reward of +2.7m Speed, $400k, and the egg takes 3m to grow in the pen. That reward is the reason low-income eggs are still worth stealing early: the speed bonus is what gets you into the next zone.

Epics are the mid-tier of their zone — a good candidate for your first mutation roll because the base rate is high enough to matter.