✨ Basic Meaning
🎯 Primary Function
📋 Grammar Structure
🎭 Usage Contexts
Can be used in formal contexts, especially in written reports or descriptions of events, but less common in highly formal speech.
Frequently used in both casual and slightly formal spoken Japanese to describe sudden occurrences.
Commonly found in narratives, news articles, and descriptive writing.
Widely used in spoken Japanese.
💡 Common Applications
📌 Important Points
⚠️ Common Mistakes
🏛️ Cultural Context
🔍 Subtle Differences
📝 Conjugation Notes
Always attach to the past tense (た形) of a verb. とたん and とたんに are generally interchangeable, with とたんに perhaps sounding slightly more formal or emphasizing the timing aspect slightly more, though the difference is minimal in practice.
🔊 Pronunciation Tips
Pronounce とたん / とたんに smoothly after the verb た形. The “to” is short.
🧠 Memory Tips
Think of 「とたん」 as “the INSTANT that…”. Visualize something happening the very moment something else finishes. The 「と」 part can remind you of the quick “pop” of something happening instantly.

I’m a software engineer based in Japan, with experience in developing web and mobile applications. I’m passionate about technology, especially in DevOps, AI, and app development using platforms like AWS, Flutter, and Node.js. My goal is to build a website that shares knowledge about the Japanese language and IT, helping everyone learn and grow more easily in the digital era.