Shouta Handa is a jobless 25 year old who is sick and tired of his boring life. One evening, at the class reunion, he gets to meet all of the cute girls that used to be his classmates. He soon discovers that they are all successful with interesting careers, and even more importantly—really beautiful now, with bigger curves. Unfortunately, it seems that they are all aware of his boring, unsuccessful life, so they mock him and call him a loser, just like in the old days. Everything changes when Shouta goes for a walk to have a smoke and accidentally falls into the school swimming pool. This triggers a supernatural phenomenon that takes him back ten years into the past. He finds himself in the same swimming pool during swimming class, surrounded by his female classmates in bikinis. How is Shouta going to deal with their cuteness and closeness now that he is a grown man in a boy's body?

The series began in the middle of a game of hide and seek, as a young boy named Justin Casey (Gen) finishes counting and begins searching for his friends Angela (usually called "Angie") and Corkey Roberts (Kanna and Tsukubo Natsuyama). As he searched for the brother and sister in the wooded area, a storm occurred all of a sudden. Justin managed to sneak up on the two before the rain started pouring, forcing them to run for cover. They would eventually find a house in the wooded area, previously unseen according to Justin. At first glance it appeared nobody was home after entering the house, until they discovered a robot named Solar Ion Robot (Kadenchin), or the acronym SIR. They would soon meet the owner of the house, Professor Humphrey Bumble (Dr. Tokio Taimu), who introduced the children to his greatest creation, a time machine. Professor Bumble's attempt at recreating Benjamin Franklin's famous lightning experiment with the use of a kite flying outside the house to get the machine working only led up to SIR's temporary change in personality before sending the entire house on course for the past. The children never realized how long the journey back home would be due to Professor Bumble's misguidance and errors in time travel, but in the meantime they witnessed and participated (with little or no consequences) in numerous events in the Bible's New Testament, from John the Baptist's birth to the rise of the Apostle Paul." (Source: Wikipedia)

It is the 25th century. The dark lord has 'infected' history with time-devices that could damage history beyond repair. Genshi and his father lived in the prehistorics when they got turned into fossiles. They are discovered and Genshi gets turned back to his original state. With the help of his father, a boy Tony and a girl Sara he has to travel trough time to bring the time-devices back to the land of time so history will be saved. (Source: ANN)

Eccentric scientist Rintarou Okabe has a never-ending thirst for scientific exploration. Together with his ditzy but well-meaning friend Mayuri Shiina and his roommate Itaru Hashida, Okabe founds the Future Gadget Laboratory in the hopes of creating technological innovations that baffle the human psyche. Despite claims of grandeur, the only notable "gadget" the trio have created is a microwave that has the mystifying power to turn bananas into green goo. However, when Okabe attends a conference on time travel, he experiences a series of strange events that lead him to believe that there is more to the "Phone Microwave" gadget than meets the eye. Apparently able to send text messages into the past using the microwave, Okabe dabbles further with the "time machine," attracting the ire and attention of the mysterious organization SERN. Due to the novel discovery, Okabe and his friends find themselves in an ever-present danger. As he works to mitigate the damage his invention has caused to the timeline, Okabe fights a battle to not only save his loved ones but also to preserve his degrading sanity.