On April 16, 2015, WayForward's official Twitter account claimed that the title character of the series is approximately 16 years old in response to a fan's inquiry on the topic. This generated controversy from audiences due to the series' heavy emphasis on fanservice, including provocative depictions of Shantae herself, drawing concerns that the series was sexualizing a minor.

Following the 2015 tweet, a user on the Shantae subreddit claimed that they contacted WayForward staffer James Montagna about the controversy. According to the user, Montagna stated that the tweet on the official account was made by an intern without the approval of higher-ups, that the staff at WayForward did not work on the series under the pretense of Shantae being a 16-year-old, and that they seek to avoid doing anything with her that would make people feel uncomfortable. The Reddit post included a link to a screencap of the conversation with Montagna; both the post and image have since been deleted. Commenters on the post additionally speculated that the tweet was referring to the age of the series rather than the age of the character. Corroborating these claims, series creator Matt Bozon stated in a June 2015 tweet that although "I write her as a 16 year old," Shantae doesn't have an official age.

The controversy over Shantae's age would finally be settled in a 2020 AMA on Limited Run Games' Discord server. In response to another question about Shantae's age, Bozon clarified his remarks from five years prior, stating that he and the other developers consider Shantae an adult of ambiguous age throughout the series.