School Rumble 2

Sagara Sousuke is far from the average high school student -- not only is he highly trained in military tactics, he puts his knowledge to use in every single applicable situation (and even those nonapplicable ones.) So, when confronted with high school, he tends to turn average high school experiences into off-the-wall adventures. Love letters become terrorist threats and field trips become commando operations; his survival depends on the watchful eye of his best friend and classmate, Chidori. Together, they may just make it out of high school alive...

While visiting his hometown, junior high school student Michishio Nagasumi's life was changed forever when he nearly drowned. Though he was saved by a mermaid named San, there’s a catch -- her family is part of a merfolk mafia, and they abide by a strict rule: If a mermaid is discovered by a man, either he or the mermaid must die. That is, unless the man marries into the family! Faced with such a decision, Nagasumi can only oblige their customs and become a "happy" newlywed. Now, with a new school year around the corner, Nagasumi must find a way to deal with his new bride, keep her true nature a secret, and most importantly, escape inevitable death at the hands of San's over-protective father’s gang!