Amu Hinamori and the Seiyo Elementary Guardians continue their quest to seek out and purify X Eggs while in pursuit of the elusive Embryo—an egg said to be able to grant any wish. However, the Guardians must secure the Embryo before it falls into the hands of the nefarious Easter Corporation. As part of their plan to lure out the Embryo, Easter hires Lulu de Morcerf, an aloof girl whose ruby necklace gives her the ability to convert Heart Eggs into Mystery Eggs. These strange Mystery Eggs cannot be purified as easily as X Eggs, and they can force its owner to undergo a Character Transformation. With this growing threat, the Guardians must track down its source and put a stop to them before the matter gets out of hand. Facing insurmountable pressure from these two new objectives, will the Guardians be able to recover the Embryo while also dealing with the Mystery Eggs?

One day, Hitoyoshi Yokoya wakes up to a mysterious nameless girl dressed as a maid ringing his doorbell, asking to be his servant. With her former master referring her to the Yokoya household, she offers her expertise as an assassin. Intimidated by her background, Hitoyoshi tries to send her away; but when she leaves something behind, he rushes to return it to her and is nearly hit by a truck in the process. With her fast reflexes, the girl saves him just in time, and Hitoyoshi ends up taking her in. Ironically, the maid lacks any skills apart from the art of killing she has perfected since childhood. Nevertheless, Hitoyoshi welcomes the girl with open arms, encouraging her to leave her monochromatic past behind and experience a normal life. To seal the deal, Hitoyoshi names her Yuki, marking the beginning of her path to redemption and happiness.

Van, the fourth son of a powerful noble, is only two years old when he remembers his past life as a salaryman in Japan. With his adult brain in a young body, he's considered a child prodigy...until he displays the Production Magic skill when he turns eight. In a family that favors offensive magic, this crafting skill is considered useless in battle, and Van is banished to oversee a tiny country town in disgrace. With only his personal maid, the memories of his past life, and his worthless magic, can Van improve the fortunes of this little village—and himself? (Source: Seven Seas Entertainment)

Osamu and Youko Sonoyama want more than anything to adopt every child from Soramame House, but the wealthy couple can only pick one due to their increasingly old age. While they contemplate this delicate decision, one child's alluring beauty and gentle soul instantly draw them in. Two months later, the Sonoyamas welcome 13-year-old Hitori into their warm and loving home. However, Hitori's humble and overly polite exterior is merely a masquerade. In reality, Hitori is a carefully crafted character played by identical twins Migi and Dali. For them, being the ideal child of this kind couple is merely a stepping stone to infiltrating a certain quiet town. While dutifully protecting their cover, the twins work toward their true objective: to discover the truth behind a past incident that left them with a burning desire for vengeance.