>>19714580>What Causes Gastritis?>Gastritis can be caused by irritation due to excessive alcohol use, chronic vomiting, stress, or the use of certain medications such as aspirin or other anti-inflammatory drugs. It may also be caused by any of the following:>Helicobacter pylori (H. pylori)>Bile reflux>Infections caused by bacteria and virusesEither Reimu is bullimic, skipped way too many meals or ate street food from the gutter.
I'm betting on bullimic and skipping meals.