If you're looking for manga similar to Senran Kagura: Spark!, you might like these titles.
Chigachi Fuuta an ordinary high school student who really admires ninjas is gifted with an extraordinary legacy, namely the soul of Hattori Hanzo, a legendary ninja. But because of that legacy, Chigachi Fuuta is targeted by various shinobi and ninja who still survive in the modern era. Can Chigachi Fuuta overcome these obstacles?
Hajime has lived in fear of the monsters lurking in the shadows that only he can see. But after meeting a mysterious shadow girl who pledges to help him face his fears, he's dragged into the secret world of ninjas.
Haruhito Kasuke was ordered by his mum to find an item in the storage house. Being a shopping-holic, Kasuke's mum had caused the storage house to become a dumping ground of unknown goods. Kasuke accidentally found an old ninja katana in the storage house, and the katana suddenly changes into the form of a kunoichi. "I had waited a long time and I finally get to see you again.."
The horn growing from Raizo’s forehead is proof that he’s the lost illegitimate son of the once-mighty Katana family. Now a band of loyal and lovely female ninjas devises a scheme to elevate their newfound master to greatness. But does this shy outcast have what it takes to rule the kingdom and deal with a bevy of beautiful ninja girls?
Shinobu is just an average schoolgirl and most certainly not a ninja—at least, that is what she claims. Class representative Hitoyoshi Kageyama finds this hard to believe though, as he is the only person to regularly see her scaling walls, throwing shuriken, lobbing smoke bombs, and disappearing without a trace. Despite being an expert at combat and infiltration, Shinobu is completely inexperienced when it comes to friendship and romance. She accordingly struggles with expressing her feelings to Hitoyoshi, who is unfortunately also quite dense. Still, the two of them gradually grow closer to each other through various interactions and school activities. In the process, Shinobu also experiences life as a normal high-schooler.