Kemmy can eat people! ? A new level number 10 appears in front of Houtarou and his friends who have successfully become friends with UFOX. Its name is “XX-Rex”! However, the X-Rex has a surprising habit of eating humans. Leaving it unattended is dangerous. Houtarou runs into Gotcha, but wonders why he would do such a thing. Meanwhile, there is another shadow chasing X-Rex. They are occult writer Manabe and his daughter, Sawa. Rinne begins to identify with Sou, who is thinking about her father. But then, the evil hand of the Three Dark Sisters approaches again...! The strongest dinosaur level 10, what is its true meaning? ?