If you're looking for anime similar to Koi Puzzle, you might like these titles.
Tsubasa Sonokawa is a 15-year old high school girl who fell in love with her upperclassman when he saved her after she fainted at the train station from anemia. She thought it was a meeting of fate, and visited him at his class every day. However, he told her that her feelings were "heavy," and he dumped her. She once again meets a boy after taking over her friend Yuri's job as boy's basketball team manager. She learns that she might have more of a connection with this boy named Aki than she first thought.
Inama Mikami, a tall and handsome boy popular among girls, has shown his interest in Yui Aoi. He actively pursues Yui, troubling her and annoying her boyfriend Kazuma Hiyama.
The story begins with Hanahi, a sixth-grade girl who is neither an adult nor a child. She deals with issues such as accidentally witnessing her homeroom teacher kissing, and worrying about experiencing physiological changes before her friends.
Short, athletic Hikaru Suzuki has just started his first year at junior high school, and things couldn’t be more eventful. He’s reunited with his sisterly childhood friend Chihiro Itou and had a glance at the wealthy, egotistical other Suzuki named Shinobu. However, most importantly, Hikaru’s first day of school yields another life-changing encounter: his first meeting with the shy would-be actress Sayaka Hoshino…
The romantic comedy centers around Makoto Kisaragi, a 15-year-old girl whose "special ability" is her persecution complex. She was raised well but in relative obscurity compared to her big sister, a famous model. Despite her negative personality, Makoto vowed to become popular when she entered high school, but things did not turn out quite so well for her. One day, she meets Iriya, Mr. Popular in their class, and they become friends.
Middle school left Uka Ishimori with nothing but scars—to the point where she's forgotten how to laugh or cry or even say “hello.” But a chance reencounter with a boy with lemon-colored hair invigorates her, giving her hope that maybe, just maybe, life can be that much sweeter if she finally reaches out for help.