Step 1: Recall the mnemonic behind the name: "Indradhanush" = rainbow = seven colours = seven diseases. The task is to find the option outside this set of seven.
Step 2: Lay out the seven covered conditions - diphtheria, pertussis, tetanus, childhood TB, polio, hepatitis B, and measles. Three of the four options (TB, measles, diphtheria) clearly sit inside this list.
Step 3: Japanese encephalitis is a vector-borne flaviviral disease covered by separate region-specific campaigns rather than the original Indradhanush seven, so it stands out as the exception.
Step 4: By elimination, the vaccine not part of the programme is the Japanese encephalitis vaccine.
\[\boxed{\text{Japanese Encephalitis}}\]