Kekkaishi

Kekkaishi is a supernatural action series that follows two teenagers who are tasked with protecting their school from spirits. While they are technically 'barrier masters' rather than traditional ninjas, the series shares many themes and tropes with the ninja genre, including secret societies, ancient techniques, and high-stakes battles. It is a fantastic, underrated series that balances action, mystery, and character development perfectly. It is a great choice for viewers who enjoy urban fantasy with a strong sense of community and tradition.