We propose to continue analyses of pristine silicate grains of Itokawa asteroid returned by the Hayabusa spacecraft for carbon isotopes using secondary ion mass spectrometry (SIMS). Analysis of one grain (RX-MD03-0082), allocated during AO7, has revealed a carbon abundance profile consistent with solar wind implantation into the shallow layers of the grain, and the 13C/12C ratio in the assumed implantation layer is identical to the proposed solar wind value from the SIMS measurements of lunar regolith grains by Hashizume et al. (2004). In this continuing work, we propose to analyze a few more pristine silicate grains for C isotopes with NanoSIMS in depth profile mode, in the hopes of strengthening the conclusion drawn from the AO7 study by finding similar solar wind implantation profiles and the same 13C/12C value (within errors). The new results, together with those from AO7, will allow us to infer the carbon isotopic composition of the Sun.