Monster Collection Series by Sei Itoh, Yasuda Hitoshi

Kasche may have a talent for controlling beasts, but she's got a lot to learn about self-control before she can become a full-fledged summoner. When disaster strikes, her principal chooses her to avert it. Joined by an unusual crew of allies both human and not, Kasche must recapture the relic from an evil summoner before she can use it to unlock the ancient Encyclopedia Verum and call up the most powerful monsters ever seen!

Kasches hunt for the stolen Guardian of Knowledge has led her to the once-peaceful city of Wallace, where rebellion is brewing under its Lord but the truth is more sinister than a mere coup! With the aid of mercenary Cuervo and the comely demon Nastasha, not to mention a little assistance from a mysterious and lecherous Lizard-man, Kasche must infiltrate the palace and reclaim the Guardian before it can be used to unlock the dangerous Encyclopedia Verum!

Kasche Arbadel is the most gifted yet reckless Summoner in her school. When an artifact of immense power is stolen, its trial by fire when Kasche is sent in pursuit! Centuries ago, summoners of the ancient empire transferred their collective knowledge into a giant, organic super-computer - The Encyclopedia Verum. Now, Lord Duran has tapped into the Encyclopedia, which will soon give him control over all the worlds creatures. With Kasche and friends

Final volume! Trapped in the ethereal plane of the Encyclopedia Verum's memory, Kasche Arbadel fights the toughest battle of her life. Unable to summon her usual monster allies, she has made a pact with a Curse Elemental, a spirit demon of pure evil. To stop Lord Duran, Kasche must embrace the darkness#133; but will she sacrifice her own soul in the process? She started this quest a mere student. To complete it, Kasche will become a legend!