Unit Gacha ! vs HARAKU
Price, ratings, monetisation and update history for both apps, side by side โ with what reviewers say about each.
Unit Gacha !
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โ Learn Physics Units with a Fun Gacha System Physics Units Gacha lets you practice unit breakdown, unit conversions, and fundamental physical quantities through randomly generated problems. Just tap to get a new question and continue learning at your own pace. โ Covers Essential Physics Units Practice and review a wide range of physics units: Mechanics (force, energy, momentum, pressure) Electricity & magnetism (voltage, resistance, charge, field strength) Waves & thermodynamics Derived units SI base units & physical constants Designed for students who want to study physics through units. โ Focused Explanations Where Needed Some problems include short explanations that show how units are derived from formulas. โ Random Practice Questions are generated randomly, allowing you to encounter various unit patterns and practice repeatedly. โ Simple Learning Features In-app scratch paper Learning progress is saved locally, and can be synchronized to the cloud when you sign in. Suitable for both quick review and focused practice sessions. โ For High-School Physics & Introductory University Courses A learning app designed to support the study of physics units for exams and fundamental review. โ Free to Use (Optional Paid Content) Approximately 70 problems are available for free Additional problem sets are available as optional paid upgrades
HARAKU
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HARAKU is an interactive educational app that visualizes the physics of waves in real time. Designed for students, teachers and anyone curious about science, it lets you control how waves behave just by moving sliders, so you can intuitively connect the equations with what you see. Developer: Fuji Bit Inc. HARAKU is the waves edition of the "-raku" physics simulation series. It helps you understand the wave concepts taught in middle school, high school and university physics as moving pictures, not just formulas. 12 simulations in 3 categories: - Wave basics - Superposition: Combine two sine waves and watch them reinforce or cancel. Change the amplitude, frequency and phase of each wave independently to see the principle of superposition. - Reflection: See the moment a traveling wave reflects at a boundary. Switch between a fixed end (phase inverts) and a free end (phase is kept), with the incident, reflected and total waves shown in three layers. - Standing waves: Watch standing waves on a string fixed at both ends while changing the harmonic. Check the positions of nodes and antinodes and the effect of tension and damping. - Fourier synthesis: See how square, triangle and sawtooth waves are made of sine waves (harmonics). The more terms you add, the closer the sum gets to the target waveform. - Sound waves - Beats: Overlap two waves with slightly different frequencies and feel the beats. The envelope clearly shows how the amplitude changes. - Doppler effect: Drag the source and see the wavefronts bunch up in front and spread out behind. Go past Mach 1 to create a shock wave. - Air column resonance (new): Switch between closed and open pipes and change the length, air temperature and resonance number to see the resonant frequency and wavelength. The motion of air particles (a longitudinal wave) is shown next to a graph that draws the displacement as a transverse wave, so you can find the nodes and antinodes. - Waves in a plane & light - 2D ripples: Tap the screen to place sources; a numerical solution of the wave equation draws the interference pattern in real time. - Interference: See the lines of reinforcement and cancellation made by two point sources. The fringe spacing changes with the source separation, frequency and speed. - Diffraction: See waves spread through a slit according to Huygens' principle. The ratio of slit width to wavelength changes how strongly they diffract. - Refraction: Visualize Snell's law, including how waves bend at a boundary and total internal reflection at large angles. - Thin-film interference (new): See why soap films and oil slicks shine in color by changing the film thickness, refractive index, angle and what lies below (air or glass). The phase shift on reflection, the color seen under white light, a color-vs-thickness strip and a reflectance-vs-wavelength graph are shown together. Features: - Clean, easy-to-read design (dark and light themes) - Home screen organized by category - Intuitive parameter sliders: touch, try and understand - An explanation sheet with formulas for every simulation - On iPad in landscape, the canvas and control panel are shown side by side - 16 languages (Japanese, English, Chinese Simplified/Traditional, Korean, Spanish, Portuguese (Brazil), German, French, Hindi, Indonesian, Russian, Italian, Turkish, Thai, Vietnamese), following your device language - No sign-in: start exploring right away Price: - Free - In-app purchases: none - Subscriptions: none - Ads: a banner ad by Pangle at the bottom of the screen
Screenshots
Verdict
The clearest difference is in-app purchases: HARAKU at none against Unit Gacha !'s 2. HARAKU also leads on update cadence (every 10 days vs every 3 weeks). Unit Gacha !'s advantage is ads (none vs shown) and iOS requirement (13.0 vs 15.0). On price and device support there is nothing between them.
Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS
Both are free to download. Unit Gacha ! sells 2 one-off in-app purchases. HARAKU asks for nothing beyond the download.
Unit Gacha ! ships an update every 3 weeks, HARAKU every 10 days. The most recent releases landed on October 11, 2026 and October 25, 2026 respectively.
| Parameter | Unit Gacha ! | HARAKU |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 3 weeks | Every 10 days โ better |
| Ads | No โ better | Yes |
| In-app purchases | Yes | No โ better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 โ better | 15.0 |
| Further details โ not scored | ||
| Size | 47 MB | 24 MB |
| Age rating | 4+ | 4+ |
| Developer | Shunsuke Nakamura | Fuji Bit Inc. |
In-app purchases
Unit Gacha !
- Unlock all mechanics problems$5.99
- Unlock all electromagnetic problems$5.99
HARAKU
No in-app purchases









