Short answers, pulled from the story.
CoroCoro Comic was founded in 1977 and is published by Shogakukan. It launched as a magazine dedicated to the Doraemon manga, which had previously been serialized across six separate Shogakukan elementary school magazines.
CoroCoro Comic had sold 400 million copies as of April 2017. That figure places it among the best-selling comic and manga magazines ever published.
CoroCoro comes from a Japanese phenomime meaning rolling, and also represents something spherical, fat, or small. The name reflects a belief that children are drawn to such qualities.
The Game Boy title Pocket Monsters Blue was sold exclusively through CoroCoro Comic at first. That exclusive sale helped the game reach its earliest audience and contributed to the magazine's monthly circulation rising from 630,000 in 1995 to a peak of 1,800,000 in 1997.
On the 20th of November 2020, Guinness World Records recognized Tariji Sasaki as the longest-running cover designer for a children's magazine.
Each issue is A5-sized, about 6 centimetres thick, and runs to 750 pages. New issues are released on the 15th of each month, or earlier if the 15th falls on a weekend.