Short Short: Rainy Season Fortune-telling

I'm bored.
I threw down my brush. "Watch it," Grandpa, who was copying sutras next to me, warned. "You still have three more sheets to go."
"I don't want to. It's just the same thing over and over."
"You improve because you write it repeatedly."
"Then make it something a bit more useful."
"Useful?"
"Yeah. 'Today is a sunny day,' 'Today is a sunny day.' It's meaningless. Besides, it's not even sunny."
The sound of rain poured down. Grandpa gave a wry smile.
"Then, how about this?"
He took my brush and quickly wrote six characters.
"Tomorrow is a rainy day."
"What's that?" I asked.
"Fortune-telling," he said with a grin.
"It's the rainy season, so that's obvious."
"I suppose so."
Grandpa wouldn't engage with me any further. I copied the new sample, but the next day I went back to the original one. I felt that 'useful' meant something else entirely.

"I'm off."
At the entrance, I waved at the framed photo of Grandpa, who passed away last year.
"Today is a sunny day."
I felt like I heard Grandpa's voice say, "Go on then."

Short Short No. 799

I am participating in Nika Tahara's weekly short short note.
This week's theme is "Rainy Season Fortune-telling."