Shakugan no Shana, 11eyes Recommendations
Both follow male protagonists fighting in different dimension zones. Shakugan no Shana and 11eyes both have dark undertones to their plot.
In 11 eyes, a group of students are sucked into a different dimension of the world where time is stopped. Similarly, in Shakugan no Shana, Flame haze can put up a fujutsu (stops time also) which encompasses a specific area and also turns everything red too.
The male protagonists of both series (Kakeru from 11 eyes and Yuji from SnS) are fighting to protect their loved ones (although Shana is more like the protecting one in SnS).
If you are a person that really like sword fighting + magic and different dimension than you will like this anime for sure.
11eyes and Shakugan no Shana are action and supernatural anime that are very similar in feel and they focus on high school students and their problems dealing with everyday life and monsters trying to kill them. Both series have very similar settings that feature main protagonists that have a special power hidden inside them and girls that wield swords in order to fight off an infinite hord of monsters in a seemingly different world - The Red Night in 11eyes and the Fuzetsu that are always setup before battles in Shakugan no Shana. If you liked watching one of the series you wont regret trying
Both have dense main characters who are special in some way. The characters fight in another world and are chased by some eeeevil organisation. Both are love triangles with a red head which uses swords and an annoying useless brown haired girl. Both try to be serious but fail miserably.
Both groups of people are fighting against some other- worldly monsters. The fights all take place in another parallel dimension where the sky would turn dark red whenever a barrier was put up. Though the romance is much better in Shakugan no Shana, 11eyes is still alright. Mainly recommended for people who watched 11eyes first.