Mugen Yuuki ~Me no Mae de, Haibokushi Ryakudatsu Sare Ochiru Shoujo~

The protagonist, Yuuichi, found a strange girl in a rainy alleyway. A beautiful girl, dressed in pink and frills. A girl who reached out and grabbed his hand, ever so gently. She held onto him, her hands shockingly cold.

Then, she told him--
"I finally found you...the source of my power..."

At that moment, the world around them crumbled, and they began to fall down. When they stopped, they were in a city Yuuichi had never seen before.

"You need to stop Renten and put an end to the 'Dream Corridor' this world has become."

[translated from official website]