May 25th Update
Disclaimer: These cards were not found from the in-game files where we normally get our leaks. However, these images are provided by Konami and appear to be legitimate. We do not know the rarities nor the release date of these cards, so we have organized the 41 cards below by archetype, such as Mayakashi, Evolsaurs and Goukis.
[box](Fire Reaper; Dark Assailant; Bolt Escargot; Emperor of the Land and Sea; Bayonater, the Baneful Barrel; Tatsunecro; Gizmek Yata, the Gleaming Vanguard; Lord Gaia the Fierce Knight; Sky Striker Mecha - Eagle Booster; Shiranui Swordmaster; Shiranui Swordsaga; Shiranui Style Solemnity; Ghost Meets Girl - A Shiranui's Story; Evoltile Gephyro; Evolsaur Pelta; Evolsaur Vulcano; Evolsaur Darwino; Evo-Force; Evo-Miracle; Evo-Branch; Evolutionary Bridge; Gouki Octostretch; Gouki Headbatt; Gouki Iron Claw; Gouki Twistcobra; Gouki Suprex; Gouki Riscorpio; Gouki Bearhug; Gouki Face Turn; Gouki Cage Match; Yuki-Musume, the Ice Mayakashi; Dakki, the Graceful Mayakashi; Shafu, the Wheeled Mayakashi; Yasha, the Skeletal Mayakashi; Oboro-Guruma, the Wheeled Mayakashi; Tsuchigumo, the Poisonous Mayakashi; Tengu, the Winged Mayakashi; Yoko, the Graceful Mayakashi; Mayakashi Return; Mayakashi Winter; Mayakashi Metamorphosis)
Keep in mind that the datamined information is speculation, and remains unconfirmed until officially announced by Konami.
Tell us your thoughts on the new cards in the comments below!