A misaligned protostellar disk fed by gas streamers in a barred spiral-like massive dense core

High-mass stars, born in massive dense cores (MDCs), profoundly affect the cosmic ecosystem through feedback processes and metal enrichment, yet little is known about how MDCs assemble and transfer mass across scales to form high-mass young stellar objects (HMYSOs). Using multiscale [40 to 2500 astronomical units (au)] observations of an MDC hosting an HMYSO, we identify a coherent dynamical structure analogous to barred spiral galaxies: three ~20,000 au spiral arms feed a ~7500 au central bar, which channels gas to a ~2000 au pseudodisk. Further accretion proceeds through the inner structures, including a Keplerian disk and an inner disk (~100 au), which are thought to be driving a collimated bipolar outflow. These multiscale structures (spiral arms, bar, streamers, envelope, disk, and outflow) have been simultaneously observed as a physically coherent structure within an MDC. Our discovery suggests that well-organized hierarchical structures play a crucial role during the gas accretion and angular momentum buildup of a massive disk.