忘れないようにメモを書きました。

N5 ない nai there isn't, doesn't have N3 メモ memo memo, note, memorandum

N3 忘 bou / wasu.reru forget, oublier, olvidar N5 書 sho / ka.ku, -ga.ki, -gaki write, écrire, escritura

N4 〜ようだ you da Indicates assumption based on evidence or impression, attaches to verb adjective or noun, means it seems that N5 〜ます masu Used at the end of verbs, polite present or future form, makes the sentence more polite N4 〜し shi Indicates multiple reasons or qualities, connects clauses or adjectives, means besides that, and also N5 〜を o Marks the direct object of an action, appears before the verb, shows what receives the action N5 〜に ni Indicates destination, target, arrival point, specific time, or person receiving an action N5 〜よ yo Sentence ending particle adding information to listener, emphasizes statement, expresses certainty or warning