A Storm Signal
Toshizou Hijikata disliked rain for strategic reasons. Bad weather was a hindrance to any militant organization, especially one that thrived on the sort of work that the Shinsengumi did. Rain also had a way of arresting one's senses, weighting one's limbs and lulling one to stay in bed a little longer and ignore all the work that needed to be done in a day.
There was one other reason why Hijikata hated foul weather and it could be found in the boy swordsman he kept at his side, the one with pale skin and the constant smell of medicine hanging around him. Damp air was bad for the lungs. Low temperatures had a habit for making delicate conditions far worse than they already were. They were short on time and every day of rain was a reminder of that but it was best to let no one, especially the boy, know.