A confident girl wants to make a living as a DJ. She has a boyfriend whom she loves very much. One day she starts to work as DJ in a bar, where she meets and falls in love with a guy who works there.

At a prestigious high school in Tokyo, the third grade D class consists of high scoring students. Their previous homeroom teacher went crazy in a short period of time and quit their job. The students in third grade D class pushes their homeroom teachers to the edge and watches their teachers collapse mentally. The students view it as a game they enjoy playing. Tsuneo Yoshizawa appears in third grade D class as their new homeroom teacher. Tsuneo Yoshizawa keeps a smile on his face, even though he is attacked verbally and physically by the students. He never loses his smile. The students' behavior gets worse towards Tsuneo Yoshizawa and they concoct a plan to kill their teacher.

Daya was studying abroad when her father died under obscure circumstances, so she hastily has to return home to Thailand. She tries to solve the mystery of her father's death with the help of Taywat, the son of the family's lawyer. They get closer to each other and their relationship eventually turns into love.

Takigawa Go gets the power to transform into Tetsujin Tiger Seven from an artificial heart and a magic pendent. To transform he utters the henshin (transformation) phrase "Tiger Spark".

During high school, Xia Ming Yue's family was met with misfortune. Her father passed away in an accident, and not long after, her mother became incapacitated by illness. Ming Yue takes on the responsibility of single-handedly caring for her mother, brother Ming Tian, and sister Ming Xing, even after discovering that she's not the Xias' biological daughter. To support her family and make ends meet, she decides to drop out of school just before the college entrance exams and instead opens a food stall. Ming Yue's classmate Xu Chong is drawn to her optimism and strength, and quietly supports her. Things are settling down for Ming Yue, but her relationship with Xu Chong makes Xu Chong's girlfriend Ding Yun jealous. Ding Yun starts scheming against Ming Yue, who is once again forced to endure hardship.