[Magically relaxing atmosphere or not, Sebastian doesn't do relaxing in the traditional sense. The closest thing, for him, is perhaps appreciating his surroundings somewhat more, or gravitating towards a somewhat less intense chore because it just seems like that kind of day.
So, basically: when Yona arrives in that flurry of cherry blossoms, the wind does a decent job of scattering a good deal of the cherry blossoms Sebastian had gathering in his basket for later jam-making.]