daijobu
Japanese drills that tell you why you got it wrong.
Other apps say "wrong, here is the answer". daijobu knows the rules that build each answer, so it names the rule your answer broke: 帰る is a godan exception, 3 + 本 becomes さんぼん.
帰る looks ichidan but is godan: る becomes り before ます, so the form is かえります, not かえます.
It makes as many items as you want, any verb in any form and any noun with any number, and it breaks down any verb form you paste.
- Decoder: paste a verb form and see each step that builds it.
- Particles: pick the particle that fits the sentence.
- Conjugation: build a verb's form, from ます to causative-passive.
- Counters: say how many, with the right counter and reading.