One of the objectives of the Attack Titan challenge is to join the Anime Club during secondary school. To do this, you must reach secondary school and join the Anime Club by visiting the Extra Curricular Activities section under your school's Activities tab.
How to reach middle school in BitLife
After creating a male or female character out of Germany, start your life. Keep aging up using the Age Up button or + icon at the middle of the menu to increase your age. Your parent/guardians will automatically send you to elementary school by the time you reach age 5. With more time, you will start attending secondary school by age 14. Remember, if you leave school for some other reason, you might reach middle school a bit late. Still, most of you will go to secondary school around the same time. So, remember the timeline. Once you reach middle school, the tag under your name on the main menu will change to your school name, secondary school.
How to join the Anime Club in BitLife
After reaching middle school, it's time to join the Anime Club. Click on your school's name and press the Activities option in your school's Activities tab. Inside the Extra Curricular window, You can find the Anime Club option at the top of the list. Click on it and join the Anime Clun to finish the given objective.
Remember, sometimes, the Anime Club option may not appear in the list of activities. In such instances, delete the current life and restart a new one, as it's all based on random probability. Additionally, the Weeb and the Anime Club are not the same. So, joining the Weeb Clique will not finish the given task.
For more on BitLife, check out How to become a member of the track team in BitLife or How to become a Librarian in BitLife on Pro Game Guides.