It's all about that string.

Better abbreviated as "danmachi", fantasy anime based on novel series of the same name. Everyone I knew started watching this series because of that string wrapped under Hestia's chest, but none of the characters seem to notice that string as anything strange. After a few episodes, most anime watchers probably wouldn't notice that string either, since all other parts about this anime is fairly solid -- great action, great animation, great voices all around. Definitely worth watching at least once.

+ Google