Old Time Buddy - To Catch a Thief (1998)

Considered a genius due to having the highest grades in the country, Miyuki Shirogane leads the prestigious Shuchiin Academy's student council as its president, working alongside the beautiful and wealthy vice president Kaguya Shinomiya. The two are often regarded as the perfect couple by students despite them not being in any sort of romantic relationship.

Irin is said to be hot-tempered and fearless — "The Devil". It's all an act, though; she puts up a mean front to build up her younger sister, Inn, by contrast. However, her young vet and neighbour Namcha couldn't care less. No matter how catty she behaves, his love persists. He's loved her ever since they were students and has no plans of changing his heart. In fact, they used to date until Irin broke things off without any explanation. Namcha has never forgotten his first love, but Irin doesn't believe his feelings are unchanged; Namcha makes it his mission to prove it to her. Love should come easy for the two, but family, work, and even friends all seem primed to tear them apart.

Shinya Yukimura and Ayame Himuro are two scientists that want to find out if love can be solved by a scientific theory. These two scientists also have feelings for each other and want to be able to solve their feelings through similar theoretical facts. With this perfect opportunity, these scientists will attempt to solve the theory of the love they express for each other.

Sorata Kanda, a high school sophomore living in Sakurasou, the den of their academy's problem children, spends his days being dragged around by the strange residents, swearing he's going to escape Sakurasou one day.

The world's number one assassin has been reincarnated as the eldest son of a family of aristocrat assassins. In exchange for being reincarnated in another world, a goddess has imposed upon him one condition. "Kill the Hero who is prophesied to destroy the world." This was to be the mission in his new life. The synergistic effect of the vast knowledge and experience he gained that made all manner of assassinations possible in the modern world, and the secret techniques and magic of the fantasy world's most powerful family of assassins turn him into the greatest assassin of all time.

When a stray black cat named Kuro crosses Mahiru Shirota's path, the high school freshman's life will never be the same again. Kuro is, in fact, no ordinary feline, but a servamp: a servant vampire. While Mahiru's personal philosophy is one of non-intervention, he soon becomes embroiled in an ancient, altogether surreal conflict between vampires and humans.

After dying of overwork in the real world, I’m reincarnated as an immortal witch, and I spend 300 years enjoying a relaxing life. At some point, though, I end up at level 99! All those years spent killing slimes to make the money to pay the bills gave me a ton of experience points. Rumors of the level 99 witch spread, and soon I’m up to my ears in curious adventurers, duelist dragons, and even a monster girl calling me her mom! I’ve never been on an adventure, but I’m the strongest in the world… What’s going to happen to my relaxing life?!

Nariyuki Yuiga is in his last and most painful year of high school. In order to gain the “special VIP recommendation” which would grant him a full scholarship to college, he must now tutor his classmates as they struggle to prepare for entrance exams. Among his pupils are “the sleeping beauty of the literary forest,” Fumino Furuhashi, and "the Thumbelina supercomputer," Rizu Ogata–two of the most beautiful super-geniuses at the school! While these two were thought to be academically flawless, it turns out that they’re completely clueless outside of their pet subjects…!?

Our MC finds out that his school requires him to join a club and during his reluctant search he stumbles upon Tejina-senpai attempting magic tricks in her clubroom. Tejina-senpai has massive stage fright however and so now that she has an audience her attempts are simply comedic.

Naoya Mukai has loved Saki Saki since grade school, and when she finally accepts his feelings, he's at his happiest. But one day, a cute girl named Nagisa Minase confesses to him! Not wishing to choose only one over another, Naoya chooses to go out with both of them!! What will be of this love triangle that challenges morality itself?