I am planning to fly to LHR via FRA. I have an Indian passport with valid UK visa

I also have valid visa from US & Japan on my passport.

Does anyone know if I still need a German Transit Visa?

This is what timatic says (It's not very clear to me if the US visa clause is valid only when traveling to US)
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Germany - Transit VisaVisa required.

TWOV (Transit Without Visa)

Nationals of India transiting through Frankfurt (FRA) or Munich (MUC), arriving from a non-Schengen Member State with a confirmed onward ticket for a flight within 24 hours to a third country which is not a Schengen Member State. They must:
- have a visa issued by Bulgaria, Canada, Cyprus, Ireland (Rep.), Japan, Romania or USA, and
- stay in the international transit area of the airport, and
- have documents required for their next destination.