"Ninja Collection" is a supernatural horror anime that intertwines multiple short stories, each centered around cursed ninja artifacts known as "Ninja Tools." These tools, imbued with dark powers, bring misfortune and tragedy to those who possess them. The narrative unfolds in a modern-day setting, where the ancient and the contemporary collide, revealing the lingering influence of these cursed objects.

The series is structured as an anthology, with each episode focusing on a different protagonist who encounters a Ninja Tool. These tools, ranging from weapons to everyday objects, are tied to the legacy of ninja clans and their dark histories. The cursed artifacts corrupt their owners, often leading to obsession, madness, or death. The protagonists, ordinary individuals unaware of the tools' malevolent nature, find themselves ensnared in supernatural events that escalate into horrifying consequences.

One recurring element is the presence of a mysterious organization that seeks to collect and contain these cursed tools. This group, shrouded in secrecy, operates in the shadows, intervening when the tools' influence becomes too dangerous. Their motives remain ambiguous, adding an air of intrigue to the overarching narrative. The organization's agents, often enigmatic and morally ambiguous, serve as a connecting thread between the standalone stories.

The characters in "Ninja Collection" are diverse, ranging from students and office workers to artists and criminals. Each protagonist is drawn into the cursed world of the Ninja Tools through chance or curiosity, highlighting the unpredictability of the artifacts' influence. The series explores themes of greed, regret, and the consequences of tampering with forces beyond human understanding. The cursed tools act as catalysts, exposing the darkest aspects of human nature and the fragility of sanity.

The tone of the series is consistently dark and foreboding, with an emphasis on psychological horror and supernatural elements. The cursed tools are not merely objects of power but symbols of the past's inescapable grip on the present. The episodic structure allows for a variety of storytelling approaches, from slow-burn tension to sudden, visceral horror. Despite the standalone nature of each episode, the recurring motifs of cursed artifacts and the shadowy organization create a cohesive narrative framework.

"Ninja Collection" blends traditional Japanese folklore with modern horror, creating a unique atmosphere that bridges the gap between historical mysticism and contemporary fears. The series avoids overt exposition, relying instead on visual storytelling and atmospheric tension to convey its themes. The result is a chilling exploration of the human condition, framed through the lens of cursed ninja artifacts and their devastating impact on those who cross their path.