"Must you always disappear all the time?" "Well, if I didn't, you'd have nothing to look forward to." She was a curse, something that didn't belong in this world. She'd lived only for herself, but she'd fallen in love with a world she didn't belong in, one filled with wars and troubles, and she'd do anything to protect it. Sinbad/Oc/Kouen

Ema and Emi are biological sisters, with Emi being the elder sister by four years. Emi knows of her adoption by Rintarou but has kept it a secret for Ema's sake. Now the two sisters will be moving in with their new family of 13 step-brothers. Is there love in the air for Emi as well?