Summary
Tsubaki Nakatsukasa serves as the Dark Demon Blade partner to Black Star. She possesses the unique ability to transform into various ninja weapons, including shuriken, smoke bombs, and, in later chapters, a katana. Although she is often disheartened by Black Star's loud and boisterous behavior, she endures it because she appreciates that aspect of his personality. Tsubaki has a forgiving nature and consistently attempts to assist everyone, even if she is unsure of how to provide help. According to Dr. Stein, her soul is highly cooperative and has ample capacity to accept others.
