One very sunny summer day...
Reimu snuck out of the shrine and went to the Human Village to play, but it suddenly started pouring rain.
As she began to rush back, she was getting soaked. The rain didn't let up, and instead just got stronger. Reimu couldn't handle it anymore, so on her way back, she took shelter in Kourindo.
"Welcome to Kourindo! ...Oh, it's you, Reimu."
Rinnosuke sent a warm greeting as he noticed someone at the entrance, but his facial expression clouded over when he recognized who it was.
"What do you mean, 'oh, it's you'? I'm a customer too, you know?"
She instinctively replied, but she had never purchased an item here, and never plans to. To be honest, calling her a customer is a bit of a stretch.
The rain outside didn't seem like it was going to stop anytime soon. Reimu started asking questions about some random items in the store, until she noticed the shiny, golden ball that he was holding in his hand.
The name of the ball is the Golden Sphere...a precious stone that has the mystic power to charm those who lay their eyes on it. Reimu subconsciously tried to touch the Golden Sphere, but Rinnosuke wouldn't allow her to do it. Reimu wanted to touch it with all her pride, but Rinnosuke resisted her. When Reimu's finger tip touched the Golden Sphere..."it" happened.
With a clap of thunder and a flash of sparks, the Golden Sphere rolled along the floor. Rinnosuke immediately tried to pick it up, but he was sucked into the light that the ball suddenly unleashed. The light shone far above Kourindo, and its impact blew the dark clouds away. Squinting from the sunlight that slipped through the window, Reimu looked around the shop.
She saw Rinnosuke absorbing the chaotic light that was unleashed from the Golden Sphere into his body with a creepy smile.
"Yeah...I'm okay... Don't worry, Reimu..."
Reimu clearly felt hostility as he spoke those words.