Basilisk: The Ouka Ninja Scrolls season 1 is available in: Japanese [Original] on Netflix Hongkong
The story takes place in the year 1614. Two ninja clans, Tsubagakure of the Iga and Manjidani of Kouga, battle each other to determine which grandson of Tokugawa Ieyasu will become the next shogun. The deadly competition between 10 elite ninja from each clan unleashes a centuries-old hatred that threatens to destroy all hope for peace between them.
In a time of peace, opposing ninja factions aim to keep their clans thriving by pinning their hopes on a young boy and girl as their heirs apparent.