"Gardens and the Warrior of Heaven" It seems to have everything your looking for.
It was sometime in the twenty-first century, when one discovery revolutionized the world further than any ever before it. This was the discovery of a nonlinear power, which lies inside of every living and nonliving organism on the planet. Its discoverers termed it Meteora. With it came the ability to tap into a clean, seemingly unlimited source of energy.
With further study, it was found that only a few genetically gifted individuals could use this power World War III was fought between these new beings and the United Governments of the world. After fighting to a stalemate, the governments and the beings who had access to this power, now known as Homospiritus, came to an agreement called the Accords.
Code 23: By law, all children born who are capable of using Meteora will be taken for safety reasons to Gardens to learn to control their powers, and serve the greater good of the commonwealth. Which meant to become a soldier in the army of the new world order. Tenchi was four years old when they came for him. Despite the best efforts by his mother to keep him hidden and safe, he was taken by force to Juneau Gardens, which is the home of the Homospiritus and the new governing order of the former United States of America, now named Juneau.
And, after six years in the Gardens’ Academy comes to an end, he seems to get his chance when, at the age of ten, Tenchi graduates. Now he is an apprentice, under the command of a Master Agent who guards, trains, and protects him and his two other apprentices, Ko and Suki. In the field as a second level of training, Tenchi has a greater degree of freedom, though under the careful guidance and tutelage of Master Agent Shaun. Eventually, he is sent on a mission where he encounters terrorists with nuclear arms who have also taken their own dark dive into the use of Meteora, only to corrupt it. Tenchi is given the chance to abandon his mission and continue his own, which has always been to return to his mother. But now he is faced with a choice, to return home or to fight to secure and prevent the misuse of The Sword of Heaven, an ancient weapon of unparalleled power forged of Meteora itself. If not kept in check, The Sword will throw the world into an apocalyptic age from which we may never recover, a fate that will visit both Homospiritus and humankind alike.
*Tenchi is the main character, Ko hates him, and they have been rivals since they first looked at each other. Tenchi loved Suki, who does't even know he exist. She is only preoccupied with two thing, being the best and furthering her career. (So you have the love, and the rivalry expect you were looking for)