Going from Tibetan to Japanese (日本語) has a composite linguistic distance of 79% (heuristic estimate). Below is the dimension-by-dimension breakdown.
Shared vocabulary, cognates, and loanwords.
Morphology, syntax, word order, cases.
Shared sounds and phoneme inventory.
Tibetan → Japanese
Sino-Tibetan ↔ Japonic
The 5 languages with the lowest linguistic distance from Tibetan:
A quick 3-question check between Tibetan and Japanese. No signup.