Confirmed by Sugimori himself!!!!
Sugimori Interview 1
Sugimori Interview 2
"Ken Sugimori, primary illustrator: I really struggled the most with the Water-type [starter] this time.
Yusuke Ohmura, illustrator: There was talk of, “Wouldn’t a sea otter be good for the Water starter?” But it was a really close decision in terms of what this sea otter would become once it evolves. In the end, we decided to have it evolve into something with a completely different appearance.
Sugimori: Of course, we want to make the starters into Pokémon that remain with the player throughout the game, so we hope to make them evolve into creatures that offer a surprise to the player. We always make an effort to throw in some twists and create third-stage evolutions that have an impact.
Ohmura: There was also talk this time about dividing the three starters into Japanese, Western, and Chinese styles of design. Tsutaaja was based on Western design, and Pokabu was rooted in a Chinese style, so I was told, “Let’s make Mijumaru into a more Japanese-style design.” Someone even asked, “Can’t you make Mijumaru into a samurai?” [laughs]
Everyone: [laughs]
Sugimori: I worried about it for a while, and I eventually went to go see the sea otters at the aquarium. I happened to catch the sea lion show while I was there, and I became aware of the sea lion’s power. “Well, let’s try blending a sea otter and a sea lion,” I thought. I came up with the idea of making the shell on Mijumaru’s stomach into a sword (katana) and using it to fight, and that’s how I completed Mijumaru and its evolution.”
Sugimori Interview 1
Sugimori Interview 2
"Ken Sugimori, primary illustrator: I really struggled the most with the Water-type [starter] this time.
Yusuke Ohmura, illustrator: There was talk of, “Wouldn’t a sea otter be good for the Water starter?” But it was a really close decision in terms of what this sea otter would become once it evolves. In the end, we decided to have it evolve into something with a completely different appearance.
Sugimori: Of course, we want to make the starters into Pokémon that remain with the player throughout the game, so we hope to make them evolve into creatures that offer a surprise to the player. We always make an effort to throw in some twists and create third-stage evolutions that have an impact.
Ohmura: There was also talk this time about dividing the three starters into Japanese, Western, and Chinese styles of design. Tsutaaja was based on Western design, and Pokabu was rooted in a Chinese style, so I was told, “Let’s make Mijumaru into a more Japanese-style design.” Someone even asked, “Can’t you make Mijumaru into a samurai?” [laughs]
Everyone: [laughs]
Sugimori: I worried about it for a while, and I eventually went to go see the sea otters at the aquarium. I happened to catch the sea lion show while I was there, and I became aware of the sea lion’s power. “Well, let’s try blending a sea otter and a sea lion,” I thought. I came up with the idea of making the shell on Mijumaru’s stomach into a sword (katana) and using it to fight, and that’s how I completed Mijumaru and its evolution.”