Keiraku

Keiraku is the rare resource used to awaken another basic chakra nature after your first /chakra test. You choose a nature you do not know yet; it does not replace your primary nature.

Natures you know before awakening	Cost
1	1 Keiraku
2	2 Keiraku
3	4 Keiraku
4	7 Keiraku

The cost therefore follows 1 → 2 → 4 → 7 until you can know all five basics. Keiraku is intentionally rare, so spend it for a nature that supports techniques you actually plan to learn rather than simply filling the collection.

Knowing the new nature gives you its affinity; it does not automatically teach that element's jutsus. Those still follow discovery and /jutsu learn.