Reiji Yamaguchi

Education is the main category at about 25% of apps, while the portfolio spans 4 categories. This is a relatively diversified portfolio strategy.

Education

1 apps · 25%

Productivity

1 apps · 25%

Social Networking

1 apps · 25%

Lifestyle

1 apps · 25%

• The primary category Education accounts for 25%. Long-tail categories can reduce single-category risk.
• The diversification score is about 0.75 (0=highly concentrated, 1=highly diversified), useful for comparing developers.

The public rating sample is thin, so reputation analysis should be treated as directional.

Apps

4

Total ratings

-

Free / paid

4 / 0

• By review volume, the leading apps include: "sheetMaker -create MarkSheet-", "teamey", "Duely – Tap to Decide".
• The visible list is free or priced at 0. Monetization may rely on subscriptions, ads, or in-app purchases; verify on the store page.

Most apps do not have enough rating data, so aggregate star ratings should be treated as directional.

• The weighted and simple averages are close, suggesting reputation is relatively balanced across apps.
• 4 apps have no public rating data, so long-tail performance is underrepresented.

The iTunes Search API does not provide review text. This card uses low star ratings with enough review volume as a proxy, and separately highlights apps with thin samples.

• No app triggered the low-rating plus sufficient-sample threshold.
• Most apps have some rating base, making star ratings relatively more stable.

The earliest listed app is "teamey", while the newest or most recent listing signal is "Bird‑Care Record App Patapata". The span is a proxy for long-term iteration capacity.

Span

2 years+

• Earliest record in this dataset: 2024 (teamey).
• Newer app signal: 2026 (Bird‑Care Record App Patapata).

These takeaways are based on public metadata and are useful for competitor research or portfolio planning. Deeper conclusions require downloads, revenue, and review text.

• Study the category mix: 4 categories show whether a main-category plus extension structure matches your resources.
• Compare reputation structure: weighted - stars vs. the leading app "sheetMaker -create MarkSheet-" and its review volume.
• For similar tools, prioritize review mining on lower-rated apps to find functional gaps; this requires store reviews or third-party data.