Well, i think you should make forum like: forum.youranimesite.com , make rankings and reword them with 1 anime series in 2 weeks or so. If you want your visitors to be active and stay on your board you have to do SEO on your pages, build links, social media optimization and so on, because the visitors that come from organic traffic (google traffic) they stay on your website and be loyal, because they searched for it, e.g.: anime series, and they love it. And the most important of all, make your website and content unique, try to get a professional them for your blog and forum, this way you'll get visitors to stay for sure.

Good luck.