It’s a similar idea to the change in English verbs(conjugation) - i.e. i climb (present tense), i climbed (past tense) i am climbing (present continuous), etc. all stem from the dictionary form of “to climb”. Japanese does the same thing with their words, and it’s part of the basic grammar you will learn when you venture into that area (as explained by everyone else).
I second Bunpro to help with grammar, it’s taught me everything i know about verb conjugations. It works on a similar idea to Wanikani, so if this works for you then again, id have a look. Even the one month free trial is definitely worth checking out. You can also find some other resources that work for you from the extra readings section in their lessons. There’s heaps of grammar resources, and pretty much all can be found in the ultimate resources list under Grammar if you wanna check that out.
Also since it’s your first time posting:
\textcolor{MediumPurple}{\huge \textsf{Hi}} {\huge \textsf{@KazumaOnline}} \textcolor{MediumPurple}{\huge \textsf{!}}
It’s great to have you here!
If you haven’t already check out the Forum Guidelines and the Wanikani User Guide .
There’s also tonnes of things on the forums to help you on your way such as The guide, The Ultimate resource list, and API and Third Party Apps.
If you have any questions, check out this thread; but if this doesn’t answer your questions, feel free to create a thread like you’re done here, or email The Wanikani staff.
Good luck, and I look forward to seeing you around!