godan verb (-mu), intransitive verb
Used for light, especially sunlight, coming into a space through an opening such as a window or gap. Intransitive.
See also: 差し込む
朝日が窓から射し込んで、部屋が明るくなった。
The morning sun streamed in through the window, brightening the room.
カーテンの隙間から月明かりが射し込んでいた。
Moonlight was shining in through a gap in the curtains.