Surprisingly the Medium Tank Type 2 Ke-To is significant to Axis and Allies online play, even though the medium tank unit is rarely ever produced by any other country. A&A credits this unit with a 75mm gun
First of all, the real life Type 2 Ke-To only featured a 37mm gun, and only 29 were ever produced, so it seems somewhat a strange selection by the game designers. The tank was largely still classified as a light tank, and perhaps goes to show how far behind was in tank development.
The Type 3 Chi-Nu would have been a more logical choice, even though it didn't see combat (held back for the invasion of the Japanese mainland) Post war inspections of the Type 3 Chi-Nu were positive, with vast improvements in armor and firepower that had been missing from all other Japanese armor.
So you're still wondering why the Medium Tank Unit is important? When compared to the other medium tank units it is still noticeably inferior:
As you can see it has the lowest health, defense, and blast damage of any of the medium tanks.
"No one makes medium tank regiments online except the AI!"
Yes, we know, and the answer to it's importance comes in an unusual place. the Artillery Tank Regiment.
All other Arty Tank regiments feature light tanks, whereas has their mythical medium tank instead. We assume this was done for game balancing reasons, since has no heavy tanks.