KanjiJLPT N3
Both

both, old Japanese coin, counter for carriages (e.g., in a train), two

Mnemonic

One tunnel cuts clean through a mountain, letting you see both sides at once. Standing dead center, both exits glow with equal light. One mountain split by one tunnel into both perfect halves—a balanced scale of stone and shadow.
Additional thoughts
Picture yourself inside the tunnel at the exact midpoint. Light from each end is identical, emphasizing symmetry and duality. The mountain is one mass, the tunnel is one passage, yet together they create two equal halves.
Quick recall
One tunnel through a mountain reveals both sides in perfect balance.

Details

The keyword for 両 is both. This kanji conveys the idea of two things together, a pair, or both sides of something. It originally depicted a balance scale with equal weights on either side, emphasizing duality and equivalence. In addition to meaning both, it historically served as a unit of currency and weight in East Asia, reflecting the concept of balanced measure.
On'yomi
りょう
Kun'yomi
てる、ふたつ

Used in kanji