良い
よい · yoi · JLPT N3 · i-adj
good
👍 Yoi sounds like Yay! — what you shout when something is good
良 is the kanji for good, also used in 良心 (ryōshin, conscience = good heart). In casual speech 良い is usually said いい (ii), but the polite and written forms keep よ: よくない (not good), よかった (that was good).
良 — pictograph of a covered grain hopper
良 originated as a pictograph of a funnel-shaped device used to clean or sift grain, with a top opening, central body, and bottom outlet. From this image of selecting good grain, the meaning extended to 'fine,' 'good,' or 'excellent.' The modern shape obscures the original object.