For B-on-project, Naoki W writes the lyrics, composes the music, arranges, and mixes everything in his home studio in Setagaya. He has a variety of vocalists, both male and female, sing along with the songs. He has collaborated with many people, including guitarists. This time's "Rain After Rain" is a love song. It tells the story of a woman catching a taxi on a rainy night in early winter, longing for her ex-boyfriend.