N5 — outside your level filter
Is said whole, with nothing composed onto it and takes no copula, so there is no paradigm to conjugate.
ごめんなさい
gomennasaiI am sorryN5expression
Related words
Readings and definitions from JMdict, © the Electronic Dictionary Research and Development Group (EDRDG), used under CC BY-SA 4.0; levels from the Tanos JLPT lists.