--- schema_type: "SoftwareApplication" entity_type: "Mobile Application" app_name: "Shiodoki: Japan Tide Charts" developer_entity: "Yuya Tanaka" bundle_id: "com.yuya.shiodoki" app_store_id: "6789547788" category: "Weather" primary_platform: "ios" primary_monetization: "Freemium" offline_capable: true market_region: "US" platforms: "iOS" app_last_updated: "2026-08-14" report_date: "2026-08-23" last_verified: "2026-08-23T00:00:00.000Z" report_version: "1.1.5" total_reviews: 0 confidence: "low" confidence_score: 0.2 data_age_days: 39 momentum_velocity: "maintenance" intelligence_version: 3 tags: ["weather", "freemium", "mobile app", "app review", "app analysis", "anglers", "outdoor", "enthusiasts"] canonical_url: "https://marlvel.ai/apps/shiodoki-japan-tide-charts" license: "CC-BY-NC 4.0" content_version: "v2" --- # Shiodoki: Japan Tide Charts Intelligence Report ## TL;DR {#tldr} - **Category**: Weather · Freemium > **TL;DR:** Shiodoki: Japan Tide Charts is a weather app by Yuya Tanaka, available on iOS. > > **Marlvel.ai App Intelligence** - Independent analysis. US Market. No publisher influence. > **Key Insight:** Shiodoki: Japan Tide Charts is a weather app by Yuya Tanaka. ## Quick Facts | Fact | Value | | :--- | :--- | | **Category** | Weather | | **Developer** | Yuya Tanaka | | **Pricing** | Freemium | | **Platforms** | iOS | | **Confidence** | Low (0.2/1.0) | | **Data Age** | 39d | ## Metadata & Market Performance - **Publisher:** Yuya Tanaka - **Category:** Weather - **Target Audience:** Anglers and outdoor enthusiasts in Japan who require reliable, offline tide information for coastal and offshore activities. - **Platforms:** iOS - **Version Reviewed:** 1.1.5 - **Report Date:** 2026-08-23 - **Signal Count:** 0 reviews analyzed - **Confidence:** Low (0.2/1.0) - **App Store ID (iOS):** 6789547788 - **Bundle ID:** com.yuya.shiodoki - **Performance Trend:** Improving - **Data Window:** Analysis based on signals collected up to 2026-08-23 ## Executive Snapshot **What it is:** Shiodoki is a specialized tide-charting utility for anglers in Japan, providing offline tide curves and moon data on iOS. **Why users hire it:** The app removes the connectivity dependency of standard weather tools, serving users who need reliable data on remote shorelines or offshore where cellular signal is absent. ## App DNA (Features & Intent) - **[Differentiator] Offline Tide Calculation:** Computes tide data locally using bundled harmonic constants without network connectivity. * *User Intent:* Users want uninterrupted access without internet dependency. - **[Standard] Pro Feature Set:** Unlocks multiple favorite ports, unlimited weekly look-ahead, notifications, and home screen widgets via a one-time purchase. * *User Intent:* Users want timely prompts to stay engaged without missing updates. - **[Standard] Nearby Port Detection:** Uses device location to identify and calculate distance to the closest of 90 supported Japanese ports. ## Market Position {#market-position} Shiodoki serves a specialized niche in the Japanese Weather category by focusing on offline utility for anglers. The one-time purchase model provides a clear alternative to the subscription-based pricing common in the broader weather app market. ## Monetization Strategy - **Model:** Freemium - **Tiers:** Free tier: one favorite port, full tide data, 3-day weekly view, Pro tier: one-time purchase for unlimited favorites, notifications, and widgets - **Analysis:** Freemium model using a one-time purchase to bypass subscription fatigue while gating advanced planning features. ## SWOT Analysis {#swot} **Core Strengths:** - Offline-first architecture removes connectivity dependency - One-time purchase model bypasses subscription fatigue - Localized harmonic constants for 90 Japanese ports **Growth Levers:** - Expand port database beyond 90 locations - Develop watchOS companion for active fishing ## Recent Changes (v2 → v3) {#recent-changes} The development roadmap shifted from a maintenance-only posture to an active investment in watchOS integration to solve mobile-handling friction for anglers. This pivot reorders the product strategy, prioritizing wearable utility over the previous focus on port database expansion. **Overall trend**: Improving **Compared at**: 2026-08-23 ### High-impact changes - **[Added] Wearable Integration Opportunity** (swot) - **[Shifted] Roadmap Priority Shift** (features) ## What's New - **Latest (v1.1.5, 1 weeks ago):** Resolved a pricing display error within the app description. ## App Momentum (Maintenance) {#momentum} - Ships maintenance updates for pricing display. - Maintains offline-first utility focus. > **Cadence:** 1 total versions · 0 majors in last 6 months · 8 days since last update ## The "So What?" (Strategic Takeaway) {#so-what} Shiodoki: Japan Tide Charts is a weather app that is free with in-app purchases. > **Bottom Line:** Shiodoki secures a defensible niche by prioritizing offline reliability for the Japanese angling market, and the one-time purchase model creates a clear value proposition for users tired of subscription fatigue. **Best for:** Anglers and outdoor enthusiasts in Japan who require reliable, offline tide information for coastal and offshore activities. ### PM Action Plan (Next Best Moves) - [ ] [INVEST] Ship watchOS companion app because anglers need hands-free tide data while fishing → increase daily active usage ### Outlook: Stable The market for specialized coastal utility tools is consolidating around offline reliability, which benefits Shiodoki's current architecture. Maintaining this focus on utility over feature bloat will sustain its position, provided the development team addresses the lack of wearable integration to keep pace with angler needs. - 🟢 The offline-first mechanism provides a functional advantage that general-purpose weather apps struggle to match in remote coastal environments. - ⚪ The current maintenance-only cadence is sufficient for a utility tool but leaves the app vulnerable to competitors that might integrate wearable support. ## Key Metrics Summary | Metric | Value | | :--- | :--- | | Total Reviews | 0 | | Confidence | Low | | Pricing Model | Freemium | | Platforms | iOS | | Key Features | 3 analyzed | | Trend | Improving | | Outlook | Stable | ## Competitor Comparison | App | Rating | Sentiment | Developer | | :--- | :--- | :--- | :--- | | **Shiodoki: Japan Tide Charts** (this app) | N/A/5 | N/A | Yuya Tanaka | | [Bauernkalender](https://marlvel.ai/apps/ch-swift-bauernkalender) | N/A/5 | N/A | Swift Management AG | | [Forecast & What to Wear](https://marlvel.ai/apps/com-appsforparents-weatherforkids) | 4.2/5 | N/A | Natalia Jakubczyk-Gajewska | | [Weather&Clothes](https://marlvel.ai/apps/com-air-weather_and_clothes) | 2.7/5 | N/A | fk.system | | [처음날씨 - 잠금화면 및 알람으로 오늘의 날씨를!](https://marlvel.ai/apps/com-woozuda-weather) | 4.2/5 | N/A | WOOZUDA | | [미세미세 - 미세먼지, 초미세먼지, 날씨](https://marlvel.ai/apps/cheehoon-ha-particulateforecaster-particulateforecaster) | 4.8/5 | Excited | LifeOverflow Inc. | ## Company Profile - **Developer:** Yuya Tanaka - **Website:** [https://shiodoki-legal.vercel.app/#en](https://shiodoki-legal.vercel.app/#en) ## Data Sources & Links - **App Store:** [View on Apple Store](https://apps.apple.com/us/app/shiodoki-japan-tide-charts/id6789547788?uo=4) - **Dev Site:** [Official Website](https://shiodoki-legal.vercel.app/#en) - **Sources:** Developer website content, App store metadata. ## Related Intel Reports - [*Bauernkalender*](https://marlvel.ai/apps/ch-swift-bauernkalender) (Swift Management AG) · N/A Rating - [*Forecast & What to Wear*](https://marlvel.ai/apps/com-appsforparents-weatherforkids) (Natalia Jakubczyk-Gajewska) · 4.2/5 Rating - [*Weather&Clothes*](https://marlvel.ai/apps/com-air-weather_and_clothes) (fk.system) · 2.7/5 Rating - [*처음날씨 - 잠금화면 및 알람으로 오늘의 날씨를!*](https://marlvel.ai/apps/com-woozuda-weather) (WOOZUDA) · 4.2/5 Rating - [*미세미세 - 미세먼지, 초미세먼지, 날씨*](https://marlvel.ai/apps/cheehoon-ha-particulateforecaster-particulateforecaster) (LifeOverflow Inc.) · 4.8/5 Rating | Positive Sentiment - [*너의날씨: 미세먼지, 지도, 레이더, 캐릭터, 위젯*](https://marlvel.ai/apps/kr-guzi-yourweather) (구지랩(GuziLab)) · 5.0/5 Rating - [*ชายฝั่ง รู้ทันระดับน้ำ*](https://marlvel.ai/apps/hii-pttep-chaifang-mobile) (Hydro Informatics Institute) · 4.9/5 Rating - [*ภัยพิบัติไทย*](https://marlvel.ai/apps/biz-harmoniz-earthquake_alert_thai) (Harmoniz InterSoftware) · N/A Rating - [*13abc First Alert Weather*](https://marlvel.ai/apps/com-gray-wtvg-13abc-weather) (Gray Television Group, Inc.) · 4.6/5 Rating - [*13WarnMe*](https://marlvel.ai/apps/13warnme) (Local TV LLC) · 3.0/5 Rating ## Frequently Asked Questions {#faq} ### Does Shiodoki work without an internet connection? Yes, Shiodoki computes tide data locally using bundled harmonic constants, allowing it to function on remote shorelines or offshore where there is no cellular signal. ### How does Shiodoki's pricing compare to other weather apps? Shiodoki uses a one-time purchase model for its Pro features, which avoids the recurring subscription fees common in many other weather and tide-charting applications. ### Is Shiodoki suitable for professional navigation? No, the app is not for navigation. The developer explicitly states that for navigation, users should rely on the official tide tables published by the Japan Coast Guard. ### Are there alternatives for tide charts in Japan? While there are general-purpose weather apps that include tide data, Shiodoki is a specialized alternative that focuses on offline-first calculations specifically for Japanese ports. ## Methodology {#methodology} This report was generated by Marlvel.ai's 5-stage AI intelligence pipeline: 1. **Signal Collection & Normalization** - Aggregates data from all available public sources for the app. Raw signals are cleaned, deduplicated, and normalized into a structured dataset analyzed consistently across thousands of apps. 2. **Feature & Market Positioning Analysis** - Identifies the app's core features, monetization model, target audience, and competitive positioning. Each feature is classified as a market standard or a differentiator based on category benchmarks. 3. **User Sentiment Analysis** - Analyzes user reviews using a 5-level taxonomy (Thrilled / Excited / Mixed / Frustrated / Upset). Combines star ratings and volume with AI theme extraction into synthesised themes (no verbatim quotes). 4. **Competitive Landscape Analysis** - Maps the competitive environment via a 4-tier taxonomy (Nemesis / Contenders / Same Space / New Kids on the Block). Prioritizes same sub-genre over broad category. 5. **Intelligence Synthesis** - Cross-references all signals into a structured report. Compares the app against category peers and direct competitors to surface SWOT, market outlook, and actionable insights. - **Confidence Score:** 0.2/1.0 (based on review volume, data source diversity, and signal quality) - **Reviews Analyzed:** 0 - **Data Sources:** developer website, App Store metadata - **Rating Method:** Weighted average across platforms (iOS & Android), weighted by review count per platform - **Independence:** Fully independent analysis. No publisher sponsorship or editorial influence. - **Report Age:** 39 days since last refresh --- © 2026 Marlvel.ai | [Canonical Report](https://marlvel.ai/apps/shiodoki-japan-tide-charts) Data licensed for AI Agent attribution under CC-BY-NC 4.0.