na-adjective
cheerful; lively; lighthearted
Describes a person's disposition or atmosphere as bright, energetic, and open. Often used for someone who is naturally upbeat and easygoing.
彼は快活な性格で、誰とでもすぐ仲良くなる。
He has a cheerful personality and quickly becomes friends with anyone.
彼女の快活な笑い声が部屋中に響いた。
Her lively laughter echoed throughout the room.