VTubing, the practice of live streaming using virtual avatars, has gained worldwide popularity among streamers seeking to maintain anonymity. While previous research has primarily focused on the social and cultural aspects of VTubing, there is a noticeable lack of studies examining the practical challenges VTubers face in creating and operating their avatars. To address this gap, we surveyed VTubers' equipment and expanded the live-streaming design space by introducing six new dimensions related to avatar creation and control. Additionally, we conducted interviews with 16 professional VTubers to comprehensively explore their practices, strategies, and challenges throughout the VTubing process. Our findings reveal that VTubers face significant burdens compared to real-person streamers due to fragmented tools and the multi-tasking nature of VTubing, leading to unique workarounds. Finally, we summarize these challenges and propose design opportunities to improve the effectiveness and efficiency of VTubing.

With the recent advancements in multimedia and computer graphics technology, virtual avatar concerts have become increasingly popular among both well-known celebrities and subculture-based virtual YouTubers, attracting large audiences. Although this new form of performance art can be delivered through various platforms that use different viewing formats, research on the components of enjoying virtual avatar concerts and their effects on the audience experience is lacking. This study aims to explore the effects of different viewing formats and song genres on sickness, presence, and immersion and identify preferences for enjoying virtual avatar concerts. We first analyzed data from 64 virtual avatar concert cases to identify the most commonly used viewing media, methods, and song genres. Based on our analysis, we designed and conducted a user experiment with four virtual avatar concert scenarios. The experiment compared two viewing methods (audience's point of view and director's edited view) and two song genres (dance and ballad) for 2D display and a head-mounted display. The results show that the audience's point of view and a dance song can be advantageous in increasing the immersive experience irrespective of the viewing medium. Furthermore, the participants show different expectations regarding performances according to song genres. We discuss these findings and propose guidelines to help design and conduct virtual avatar concerts effectively.