If you're looking for manga similar to Doby & Disy: Detective Kubi, you might like these titles.
Ichiko and Niko are a cute pair of twins. Their father is an inventor and raises them alone. He develops all kinds of crazy machines to improve the lives of his daughters. However one day, a lightning falls on the house and the father is transformed into a plush! Fortunately the teddy speaks, moves and continues his work of invention. As such, the lives of Ichiko and Niko become more fun!
Satsuki, her younger sister Mei and their father have just moved to their new home in the countryside, where grand adventures await them. One day while playing outside in the garden Mei encounters a small creature and decides to follow it. After chasing it through the bushes Mei eventually finds herself at the base of a large Camphor tree and as she drops through a hole in its roots, she lands on the stomach of a large, sleeping forest spirit named Totoro. The two sisters befriend the gentle spirit and are soon introduced to a world more fantastical than they could ever imagine, from playing with soot spirits to meeting a Catbus, to flying through the air and even making the trees grow. However when Mei disappears, Satsuki must call on the help of her new friends if she wants any hope of being able to find her sister...
Kokoro found a strange machine in her basement, as well as a variety of problems to solve!
In the year 2020 it became possible to travel to the "electric monster world" using special portable telephones. Making friends and sharing telephone numbers with the "electric monsters" became popular among humans. Our protagonist, Shigeki, is one such person. Although he originally arrived in the electric monster world on accident, he became determined to travel the world with his new electric monster companion Kuribute, and make more new friends while he was there.
Follows Shiro Kyoda, a young boy from Tamiya City and a student of the Bandai Elementary School. Shiro is an enthusiast of plastic model kits and "Plamo Simulation", a plastic model battle game. Shiro's dream is to become the representative of Japan in the World Simulation Tournament and be able to fight in the finals in the Battle of Hobbytopia.