High School DxD

Synopsis

Rias decides that it is time for Issei and Asia to have servant familiars. The school's student council visits the club room, and Issei learns that they are another faction of devils. Since only one group is allowed to enter the world of familiars per month, the two groups compete to see who gets to go first. As they compete in a tennis match, what starts as a normal human competitions turns frightful as Rias and Sona use magic to enhance their moves. They end up destroying much of the equipment, leading to a draw. Rias's group later wins in the dodge ball match, allowing them to pick new familiars first. During the search for familiars, they are greeted by Master Familiar Towji. He guides Issei and Asia throughout the forest and shows different creatures they can choose. The group later finds a Sprite Dragon, a familiar difficult to obtain. Suddenly, slime litters the forest and obliterates clothes. Issei wants to make slime as his familiar and uses Asia to protect it. He is knocked out by the Sprite Dragon, who has taken a liking to Asia. In the end, Asia accepts him as a familiar while Rias notes Issei still has ways to go. 

(Source: Wikipedia)