  The existence of the axion is a unique solution for the strong CP problem,
and the axion is one of the most promising candidates of the dark matter.
Investigating Solar Axion by Iron-57 (ISAI) is being prepared as a complemented
table-top experiment to confirm the solar axion scenario. Probing an X-ray
emission from the nuclear transitions associated with the axion-nucleon
coupling is a leading approach. ISAI searches for the monochromatic 14.4 keV
X-ray from the first excited state of 57Fe using a state-of-the-art pixelized
silicon detector, dubbed XRPIX, under an extremely low-background environment.
We highlight scientific objectives, experimental design and the latest status
of ISAI.
