What banmal means. Banmal (반말) is casual, non-honorific speech. Being older does not automatically give someone a universal right to use it, and being the same age does not guarantee that both people will immediately switch to it.

Look at the current speech pattern. If both people already use polite speech, an abrupt one-sided switch can feel presumptive. An explicit invitation such as “말 편하게 하세요” can change the situation, but tone, role, and setting still matter.

Work and school can override closeness. A boss, teacher, senior, client, or formal group may keep polite speech even when people are friendly. In uncertain situations, maintaining polite speech and letting the relationship establish its own norm is the safer starting point.