Games like Imperishable Memories

If you finished Imperishable Memories, the closest matches are Bullet Soul Infinite Burst, Giga Wing 2, Run=Dim: Return to Earth, Soreyuke Burunyan-Man Portable - Torimodose Ai to Seigi to Kibou no Tsunyakan and Aeternum. All 8 share its shooter genre and are ranked by how closely their themes and modes overlap.