The Item Inspector script offers search function that would meet your requirements. You can select a base table and search on it. The most useful tables for search are:
- All Learned Item will let you search on items you have learned
- All Wanikani Items will let you search on all items regardless whether they are learned on not.
Once you have selected a table you can une the temporary filter drop down to pick a search function to perform a search. Fell free to explore available options.
Disclosure: I am the author of Item Inspector.