This study aims to address the issues surrounding the volcanic activity records of Aso Volcano during the historical period, particularly in the early 19th century. Many historical accounts of Aso's volcanic activity are either based on unverifiable sources or suffer from misquotations in previous studies, making it difficult to revisit and reassess the nature of the eruptions. To resolve this problem, historical records from the early 19th century were meticulously collected and analyzed, with a focus on reconstructing an accurate timeline of volcanic events during this period. Through a comprehensive search, key documents were uncovered that detailed the volcanic activity of Aso Volcano, including the eruptions of 1815, 1826, 1830, and 1854. Each of these records was carefully evaluated for authenticity and reliability. The analysis revealed several critical findings: first, the eruption of 1815 was preceded by signs of volcanic unrest that began as early as 1814, indicating a longer lead-up to the eruption than previously thought. Second, the eruption of 1826 was supported by highly credible accounts, confirming the scale of the event and the damage it caused. Third, the eruption of 1830 was identified as a Strombolian-type eruption, followed by sustained volcanic activity that continued for a decade. Lastly, the study uncovered previously unknown human casualties during the 1854 eruption, highlighting the significance of this event, which had not been thoroughly documented in earlier research. By examining these primary sources, the study was able to reconstruct a more accurate and detailed history of Aso Volcano's volcanic activity in the early 19th century. This not only clarified the extent and nature of the eruptions but also brought to light previously unknown impacts and developments in volcanic activity. The findings contribute to a deeper understanding of the historical volcanic behavior of Aso Volcano, filling gaps in the current literature and correcting inaccuracies in prior studies. This research provides a foundation for future investigations into the historical and geological significance of Aso Volcano's eruptions, particularly in relation to understanding long-term volcanic patterns and risk assessments for the region.