Lily Baker, a young English girl, decides to go to an arcade on Valentine's Day. She is determined to win a stuffed animal from a claw machine; but even after attempting it for hours, she is unable to get her hands on the prize. Just as she is about to give up, arcade employee Renji Kusakabe steps in and wins the prize for her as a present to celebrate the special day. Due to her cultural background, however, Lily mistakes his action as a declaration of love! With Lily returning to the same arcade in the hopes of seeing Renji again, the two begin exchanging a notebook to learn more about each other and their respective cultures. This marks the start of a friendship filled with gaming, but that is not enough for Lily, as she swears to make Renji fall in love with her!

Aimless daydreaming in high school is an ordinary part of growing up. But once graduation comes, suddenly there are bills to pay and a higher education to tackle. Even so, Midori Nagumo never quite stopped dreaming—even after entering college—as she still wants to have fun while ignoring her responsibilities. Contrasting Midori's recklessness is her supposed best friend Niikura, who is the complete opposite of Midori and has a goal of becoming a photographer after college. However, Niikura is often pulled into Midori's schemes, which leads them to meet Wako Izumi, a tenacious, yet airheaded classmate who is always taking pictures of things she finds fun. The trio ends up living together in the same apartment and attempt to navigate their lives in the city of City, where unexpected and out-of-the-ordinary things occur daily.

Uta Koi tells the "super-liberal interpretation" of the Hyakuninisshu anthology compiled during Japan's Heian period of 100 romantic poems from 100 different poets such as The Tale of Genji's Murasaki Shikibu.

Dr. Hell and his Mechanical Beasts are back, and they're more dangerous than ever before. Kouji Kabuto and Tetsuya Tsurugi fight a fierce battle against these hellish machines, which are under the command of Baron Ashura. Unfortunately, they are defeated, with Kouji's Mazinger Z being captured and Tetsuya's Great Mazinger seriously damaged by the enemy. The devious Dr. Hell quickly converts the captured robot into Ashura Mazinger and uses it to attack the Photo Power Lab. At the same time, Kouji is missing in action, which leaves Testuya to defend the lab in the damaged Great Mazinger. But the forces of Dr. Hell are too strong, even for a brave pilot such as Tetsuya, and all seems to be lost. The battle seems to be drawing to a close, until an overpowering blast fired by an unknown robot destroys the entire Mechanical Beast army. Could this mysterious robot be the legendary Mazinkaiser, and who is piloting it?