  This paper presents a multiwavelength Sun-as-a-star analysis of the M8.7
flare on 2022 October 2, which were associated with a filament eruption and the
following coronal mass ejection. The Sun-as-a-star analysis was performed using
H$\alpha$ data taken by Solar Dynamics Doppler Imager on board the Solar
Magnetic Activity Research Telescope at Hida Observatory, Kyoto University and
full-disk integrated extreme ultraviolet (EUV) spectra taken by the Extreme
ultraviolet Variability Experiment (EVE) on board the Solar Dynamics
Observatory. The Sun-as-a-star H$\alpha$ spectra showed blueshifted absorption
corresponding to the filament eruption. Furthermore, the EVE O {\sc v} 629.7
{\AA} spectra showed blueshifted brightening, which can also be attributed to
the filament eruption. Even when the blueshifted absorption became almost
invisible in the Sun-as-a-star H$\alpha$ spectra, the O {\sc v} blueshifted
brightening up to $-400$ km s$^{-1}$ was still clearly visible. This result
indicates that even when the shifted components--which are expected to
originate from stellar eruptions--become almost invisible in the spatially
integrated stellar H$\alpha$ spectra, the erupting materials may still be
present and observable in EUV spectra. Additionally, the Sun-as-a-star
H$\alpha$ and O {\sc v} spectra exhibited redshifted absorption and
brightening, respectively, during the decay phase of the flare. These
components probably originate from the post-flare loops, providing clues for
the multi-temperature nature of the post-flare loops in the spatially
integrated observation. Our Sun-as-a-star results suggest that the combination
of H$\alpha$ and EUV lines allows the investigation of the multi-temperature
structure and temporal development of stellar active phenomena even in
spatially integrated spectra.
