Assassination Classroom Season 1 contains anime episodes 1-22 and is from Studio Gokumi.

At Kunugigaoka Junior High School, class 3-E is the lowest of the low. With abysmal test scores and no future prospects, they've been given up on and hidden away from the main campus at the top of a deserted mountain. But when a tentacled creature with a thirst for destruction becomes their new teacher, they've got a brand new assignment to get them inspired about school: take him out.