Kaede Yuasa

In a world bursting at the seams with moe monsters and humanoids of the horned sort, which brave heroes will take it upon themselves to review the beastly babes of the red-light district? Can only one be crowned the ultimate title of best girl? Behold the most tantalizing of trials.

Natsuo is a high school boy who is experiencing the crushing despair of unrequited love. To make matters worse, the person he is in love with is his teacher, Hina. In an attempt to lift his spirits, he attends a mixer where he meets a girl named Rui. The two sleep together, expecting never to see one another again, but fate has other plans. His life suddenly becomes more complicated when his father comes home and announces he has remarried a woman with two daughters whom Natsuo has met before: Hina and Rui!

The two main characters, Katsumi and Isami Minato, are brothers who live with their younger sister and father who runs a specialty store. One day, they found the R/B Gyro and R/B Crystals, which transforms Katsumi into Ultraman Rosso and Isami into Ultraman Blu.