Since 2013, Yoshiaki Koizumi works as a director for 1-UP Studio[1].
Yoshiaki Koizumi plays an important role during E3 2019's Nintendo Direct presentation, announcing Bowser as the new president of Nintendo's North American branch. Bowser, King of the Koopas, appears onscreen, proud to hear his name. Yoshiaki Kozumi says the Koopa King is the wrong "Bowser", as Doug Bowser walks onscreen, much to the former Bowser's shock and confusion.
Nintendo Power interviewed Yoshiaki in a special section mainly for Super Mario Galaxy. In the interview, he revealed the following facts about the development of the game:
Yoshiaki had wanted to always create a boss fight in which the character had to climb up on top of the boss. He tried to create Ganondorf this way in The Legend of Zelda: Ocarina of Time but decided the fight would be too difficult. Later, in Super Mario Galaxy, he was able to try this concept again with the boss Megaleg.
Yoshiaki wanted to create more missions in which Luigi had to be found by Mario, but ran out of time and scrapped them.
Yoshiaki was the writer of Rosalina's Story in Galaxy. He wrote the story at night, without anybody knowing what he was doing. The following day, he presented the story to Shigeru Miyamoto, who was surprised when Yoshiaki told him nobody knew about it.
Yoshiaki also states that he would like Rosalina's story to be made into a real children's book.