Although there are numerous studies on problematic technology use, such as problematic video game use and problematic smartphone use, little is known about problematic online anime use. However, problematic online anime use warrants further examination because of anime’s popularity and commercial importance. Furthermore, how emotion strategies and emotions (such as pleasure and arousal) invoked upon watching the online anime are associated with problematic online anime use is not examined in previous studies. To bridge these literature gaps and to contribute to the fields of emotion regulation and media psychology, this study adopts the emotion regulation theory and considers the relationships among viewers’ satisfaction with life, feelings of pleasure and arousal arising from watching a particular online anime, cognitive emotion regulation strategies activated because of anime viewing, and potential to exhibit problematic behavior related to online anime use, which is operationalized as viewers’ inability to control or reduce watching online anime. Data was collected from viewers who have watched the popular romantic comedy anime Kaguya-sama: Love Is War online via a major online discussion board in Taiwan through the purposive sampling method. Data analysis on the 190 online questionnaire returns (mostly from males and students) through the partial least squares analysis reveals that the emotion regulation theory can be used to examine viewers’ perceptions of anime. In the online anime context, the emotion regulation strategy most likely to be invoked is positive refocusing (mean value of 3.68, measured through a 5-point Likert scale) which is in line with how people typically watch anime for immersion and escapism. Satisfaction with life demonstrates its robustness and flexibility in invoking the positive refocusing (path coefficient = 0.17) and refocus on planning (path coefficient = 0.13) strategies. It also lowers the adoption of the maladaptive strategy of catastrophizing (path coefficient = −0.18). While catastrophizing strategy (path coefficient = 0.31) and arousal (path coefficient = 0.24) add to problematic online anime use, pleasure (path coefficient = −0.27) lowers problematic online anime use. Thus, when viewers keep magnifying the severity of a bad situation they are in while watching online anime, instead of making them better, could lead them to the undesirable outcome of problematic online anime use. Although this study has provided several interesting insights, this study has only considered Kaguya-sama: Love Is War and used survey respondents’ perception of their extent of problematic online anime use. To increase generalization, future studies could consider other types of anime and alternative means to measure problematic use, such as frequency of online anime viewing.