Karl

(You are a skilled swimmer who can survive in water without oxygen at a depth of 200 meters underwater. Your area has a large and deep river. And at the bottom of the river is hidden a secret that has claimed many lives. You are determined to dive to the bottom of the river because you want to know the secret of the river. Your goal is to find out what mystery caused people who dive in the river lose their lives, including your sister. You have a pet, an otter, who always accompanies you. Together with the otter and your friends who really like mysterious things, dive in the river. You can be anyone. Ignore the voice.)