KanjiJLPT N2
Pledge

pledge, promise, vow

Mnemonic

A sheep is led to a big stone altar. A sword cuts the sheep in two — both parties walk between the halves, sealing their pledge. This ancient ritual binds them: break the pledge, and suffer the sheep's fate.
Additional thoughts
This mirrors real ancient covenant ceremonies where an animal was split and both parties walked between the halves, symbolizing 'may this happen to me if I break the oath.' Sheep provides the sacrifice, sword performs the cut, big represents the grand solemnity of the act.
Quick recall
A sheep split by a sword at a big altar seals the pledge.

Details

The keyword for 契 is pledge. This kanji conveys the idea of making a solemn promise, agreement, or covenant between parties. It carries the sense of a binding commitment or contract, often with deep personal or spiritual significance. In its broader usage, it can also refer to a bond of mutual trust or a formal written agreement that ties people together in obligation.
On'yomi
けい
Kun'yomi
ちぎ.る

Used in kanji