Use the greetings from dawn until 10 a.m., but no more than 11 a.m. should be used fresh, clear tone, but if it is a close friend or someone just talking o yo u ha (Omi Hachiman yo).
Greetings from the morning until 10 o'clock, but no later than 11 o'clock in the morning, use a tone that is refreshing, if a close friend or someone who's just お は よ う (oh ha a) time.