Iczelion, the final entry in the "Icz" series, is a departure from the previous storyline in most resepcts. Throughout the galaxy, two villians destory and pillage anything in their path. Their names are Cross and Chaos, and they are ready to invade their next target: Earth. The only defense against these warriors are the Iczelions, a fusion of young girls, and Iczels, sentient body armor. Nagisa is a typical high school girl who is about to become the next Iczelion against her will, to defend the planet and save the human race! But not if she has anything to say about it...

Freshman Kaho Nikaidou is from an influential family, and as such, no one has ever said anything even remotely mean to her, for fear of incurring her household's wrath. Wishing to be around people who will not treat her as special because of her background, she leaves home to live at a dormitory for her new school year. Shortly after arriving, Kaho accidentally wanders into traffic and is saved by a tall, handsome stranger. When she asks for his name, he tells her she is weird and walks away. Having finally met the only person to ever say an unkind word to her, Kaho falls head over heels for her savior. After meeting her rescuer yet again and discovering that his name is Kanade Takahashi, she confesses her love to him. Kanade says he would like for them to be a couple, but that Kaho may not want to date him after she finds out his secret. To her shock, Kaho discovers the startling truth: Kanade is a fifth grader! Deciding that she can't date a fifth grader, Kaho intends to break up with him. But as she spends more time with Kanade, she begins to care for him even more and continues dating him. Hatsukoi Monster follows Kaho's first steps into love with Kanade, her immature, yet kind, fifth grade boyfriend.

The Kingdoms of Dolhr, Grust, and Gra band together to wage war on the rest of the continent Archanea and defeat the Kingdom of Altea. King Cornelius is slain in battle but his son Prince Marth is able to escape the invasion thanks to the sacrifice of his older sister Elice. He and a small group of retainers find refuge on the island nation of Talys, where they spend the next three years in hiding under the royal family's protection. Marth lives a peaceful life in Talys, enjoying the beauty of the island and the friendship of its pegasus-riding princess, Caeda. But he is uneasy, knowing soon the day will come that he must take up arms. That day arrives when Caeda comes to Marth and his retainers in a panic, telling him that the castle town has been attacked. After some close calls, they manage to defeat the assailants and save the city. Realizing that his presence may bring further danger to his new home, Marth decides that now is the time to set off. He journeys to raise an army with which to reclaim his kingdom.

Shun Asanaga is a 15-year-old junior high school student with an optimistic and bright personality. One day, he finds a mysterious crystal in the office of his father, who is a scientist and businessman. When Shun touches it, the world becomes distorted, and he is sent into the world of Endra. Emilio, a prince of the kingdom of Endra, is nearing his 16th birthday and despises the reigning king, Delzain. Since Emilio is now at the age when he can inherit the throne, he takes up a weapon and attempts revenge. However, because Emilio is too weak, he is captured by Delzain and put in prison. When Emilio is in grief, the wall of his cell becomes distorted and Shun appears from there with two goals: return to his own world, and complete Emilio's revenge. What future lies ahead for the two boys trying to survive in Endra, yet raised in two different worlds?