The game features a card system that focuses on character cards that represent individual characters from the anime/manga, and these character cards come with unique skills and decks.
While there are some cards with similar functions to Ritual Monsters, such as "Ritual Beast Tamer" or "Ritual Beast Ultimitzer" that can be used by specific characters, these are not classified as Ritual Cards in the game itself.
You may be thinking of the "Ritual" archetype from the Yu-Gi-Oh! Trading Card Game, which is separate from the mobile game Duelist Roses.