Frieren is the main character of the anime, "Friren Beyond Journey's End."

That's why when I saw the scene in which she was crying loudly, I was impressed.

Or colloquially people tend to say "where" I can't tell you what the grammatical difference though. I heard that "in which" is used for more specific things?

She speaks in a curt tone.

You could combine these two sentences: "She has a unique characteristic: she speaks in a curt tone." Or: "She has the unique characteristic of speaking in a curt tone."

JBut just because she speaks in a curt tone doesn't mean she is angry or in a bad mood.

That's why when I saw the scene where she was crying loudly, I was impressmoved.

Maybe "I'm touched" might sound better?

"I'm touched" works here! "I was moved" also works.

Frieren is the main character of the anime "Frieren Beyond Journey's End."

She is always quiet, and doesn't laugh out loud or cry loudly.

That's why when I saw the scene where she was crying loudly, I was impressed.

'wailing' is another word for 'crying loudly'

Frieren is the main character of the anime, "Frieren: Beyond Journey's End."

She has a unique characteristicpersonality and speaks in a curt tone.

Your sentences are correct but you can connect them for flow.

She speaks in a curt tone.

JBut, just because she speaks in a curt tone doesn't mean she is angry or in a bad mood.

She is always quiet, and doesn't laugh out loud or cry loudly.

That's why when I saw the scene where she was crying loudly, I was impressedawestruck.

Maybe "I'm touched" might sound better?

Yeah, "I was touched" would work.

Other Phrases/Words:
awestruck, astounded, taken aback

Frieren is the main character ofin the anime "Frieren: Beyond Journey's End."

She has a unique characteristic.

"Characteristic" and "character" have different meanings. I think maybe you mean that she has a unique character or personality?

JBut just because she speaks in a curt tone doesn't mean she is angry or in a bad mood.

She is always quiet, and she doesn't laugh out loud or cry loudly.

That's why when I sawI was really moved by the scene where she was crying loudly, I was impressed.

You could also say, "That's why I was really struck by the scene where she was crying loudly."

"Impressive" might not matchfit in this case.

Maybe "I'm touched" might sound better?

"I'm touched" sounds better, but to me, "touched" sounds like it has more of a nuance of feeling grateful or appreciative of something. "Touched" is often used when someone does a nice gesture for us, especially when we're not expecting it. For example, "I was touched by his kindness."

I think the word "moved" fits perfectly with what you're trying to say. We use the word "moved" when we see or experience something that affects us on an emotional level. It doesn't have the same nuance of feeling grateful, and it just means something affected you emotionally. I think "I was struck" is OK here too.

Frieren is the main character ofin the anime "Frieren Beyond Journey's End."

JHowever, just because she speaks in a curt tone doesn't mean she is angry or in a bad mood.

That's why when I saw the scene where she was crying loudly, I was impressedsobbing, I was touched/it made an impression on me.