According to data reported by the popular anime website MyAnimeList , the first episode of Attack on Titan: The Final Season was the most-watched premiere among the site's users. On Monday, 144,668 users listed the anime as "watching" on their accounts, surpassing the third season of My Hero Academia , which had registered a total of 107,042 viewers.
In response, MyAnimeList noted that spam accounts are being counted in the ranking, but even so, Attack on Titan The Final Season is still the number one premiere, even after discounting all users who listed the anime with a "1" or a "10" in the rating section.
The final season of Attack on Titan premiered on December 7th.
Source: ANN