For years, retail currency investors were known as "Mrs. Watanabes," a reference to the metaphorical housewife who invests family savings mostly in foreign exchange. Now, a younger generation of women is looking at a wider asset range in which to park investments.

Like their elders, kinyū joshi (finance girls), who are largely in their 20s and 30s, face a challenging investment landscape with bank deposits offering minimal, near-zero returns.

Unlike their senior counterparts, however, younger female investors tend to be more frugal and averse to overexposure to any one single asset class. For this reason, many of them are tapping a broader asset universe using mobile-based services to keep costs low.