The Naxi Geba script is not yet in Unicode. The script has a tentative allocation at U+1A800..U+1AAAF in the Roadmap to the SMP for the Unicode Standard. There seems to be disagreement on whether Naxi Dongba and Nakhi Geba should be considered the same script (see also the Unicode Status (Naxi Dongba) entry).
A number of proposals for its inclusion have been submitted to the Unicode Technical Committee and WG2:
1992-10-30 Moso (a.k.a. Naxi, Nahsi, Nakhi) — Rick McGowan ( Unicode Technical Report #3 R2)
2001-06-14 Naxi Geba codechart — Michael Everson ( Unofficial Naxi Geba codechart)