If you're looking for anime similar to Zero no Tsukaima: Princess no Rondo, you might like these titles. All recommendations are made by Anime-Planet users like you!
Rhiannon is the fair and gentle daughter of a village chief. Unfortunately for her, she's also exactly the sort of maiden who is needed as a sacrifice to wake the Demon King Arawn from his thousand-year slumber and is soon kidnapped for this very purpose. However, when Arawn is summoned, he decides to spare Rhiannon's life, instead killing her captor and freeing her from mind control. Taken with his kindness, Rhiannon immediately decides to marry the Demon King, making him the new village chief. All of this is bad news for Rhiannon's protective but hot-headed brother Arthur, who must now pledge his knightly service to his new Lord, Arawn. Together the three of them must journey and together they must fight, encountering new friends and new foes along the way.
Both main characters are summoned from another world/dimension. They both are sword users but in tears to tiara the main character is highly skilled from the start. They are both harems with many different women falling in love with the main character, but Zero no Tsukaima is more open about that. If you like adventure, wording fighting and magic fighting either one is a very good choice.
Fifteen-year-old Yamada has just entered high school and is gung ho about achieving her ultimate goal: to have one hundred sex partners! There’s just one problem: she’s a virgin, and she hasn’t even had a boyfriend! To get the ball rolling, Yamada decides to target a shy boy named Takashi from her school; but even though he is also a virgin and she ruthlessly aggressive with her feminine ways, it’s not as easy as Yamada hopes. Though they begin to have feelings for each other, will Yamada and Takashi ever get past first base?
Seeking a cure for his depraved masochism, Taro Sado approaches the Second Volunteer Club on the recommendation of his best friend, Tatsukichi. There he finds the help of the violent but kind Mio Isurugi who promises to beat the masochism out of him by any means necessary. Will Taro be able to survive the assaults of this upperclassman, the overly-affectionate attentions of his mother and sister, and still lead a normal school life? Unlikely. But will he get over his perverse fetish? He sure hopes so.
Sakai Yuuji thought he was a normal high school student, until one fateful day when time stopped. Watching in horror, he witnesses a monster devouring the "frozen" people around him; but luckily for Yuuji, he is saved by a sword-wielding red-headed girl that calls herself a "Flame Haze". The girl informs him that he has been dead for some time now and that his current self is merely a replacement for the human that he used be while alive. He is, she says, merely a torch whose life will come to an end when the blue flame in his chest ceases to burn. After this rude awakening, Yuuji realizes that he is able to see the flames of life in other "torches"; and after discovering that a friend of his is also a torch -- and her life is burning out faster than his – he gains the courage to live out the rest of his life with meaning. Will Yuuji be able to find his place in the world before he ceases to exist?
Yuuji and the Flame Haze Shana have thwarted several of the Bal Masque’s evil schemes, but the lives of a Flame Haze and the holder of the Reiji Maigo are never simple. While rifling through a pile of objects, Yuuji finds what appears to be a telescope; but after looking through it at Shana, an unfortunate side effect occurs: they switch bodies! Now inhabiting the flesh of the other, the two must stick it out until they can change back. What other adventures await the supernatural pair?
Both animes have the same basic elements. They are both very well done animes and if you liked/watched either Zero no Tsukaima or even Shakugan no Shana, you will enjoy watching the other.
And if you haven't watched either I highly suggest that you do, especially if you enjoy a romance anime with action, magic, and cute spunky tempermental heroines.