Shinzo will blush when Tsubame praises his shuriken throwing. He will secretly give her his share of sweet potatoes. Unlike Kenichi’s dramatic obsession or Hattori’s stoic repression, Shinzo’s romance is purely about admiration and friendship. It serves as the "prequel" to the more complex adult relationships, showing that even ninjas start with simple, pure hearts. One of the more criticized aspects of the original Ninja Hattori is the passive role of its female characters, primarily Yumiko. She is often the "prize" to be won by either Kemumaki or Kenichi. However, a deeper reading—especially in the manga and later adaptations—reveals a different story.

The arrival of —the rich, handsome, and smug rival from Tokyo—turns this gentle crush into a full-blown war. Kemumaki has all the qualities Kenichi lacks: wealth, style, confidence, and a penchant for grand, romantic gestures. He arrives in a limousine, showers Yumiko with expensive gifts, and frequently invites her to his family’s villa.

The episodes featuring Princess Yuki are a masterclass in subtext. Hattori, usually so confident and quick to act, becomes clumsy and tongue-tied. His hands tremble when holding a scroll from her. He volunteers for dangerous missions if there is a chance to pass near her village. Shinzo, ever the mischievous younger brother, constantly teases Hattori about his "princess."