冴える， 冱える， さえる
1. to be clear (of a sight, sound, colour, etc.), to be bright, to be vivid, to be crisp
2. to be clear-headed, to be alert, to be on the ball, to be wide awake
3. to look upbeat, to be perky, to be cheerful
4. to master (a skill), to excel at, to cl...
tbd