Compared to wakuwaku (わくわく, excitedly anticipating), dokidoki (ドキドキ) emphasizes a more nervous, anxious kind of excitement. It's the sound of your heart beating fast, but not necessarily in a good way. Both words describe an elevated emotional state, but the core feeling is quite different.

Consider the following scenarios:

Scenario 1: Wakuwaku

Akari has just bought her train ticket to go on a long-awaited trip. She's been planning this vacation for months. Akari's inner monologue would be full of wakuwaku: “Tomorrow, I'll finally get to see the ocean! I can't wait!" Here, the anticipation is purely positive. She is filled with bright, joyful anticipation.

Scenario 2: Dokidoki

Now, consider Ren, a student preparing to give a presentation in front of the class. He's studied hard, but he’s still very nervous. As he walks up to the podium, his heart is going dokidoki. He is experiencing nervousness and anxiety. If his presentation goes well, his heart might shift to feeling wakuwaku or even kyunkyun (きゅんきゅん, a sweet flutter). But at this moment, the dominant feeling is the nervous pounding of his heart.

Scenario 3: Kinyun kyunkyun

Finally, let's look at Hana. It's her first date. She might feel kyun-kyun, a fluttering feeling of sweetness and innocent desire as she sees her date approaching. This is a lighter, more romantic feeling than dokidoki. However, she might feel dokidoki before he arrives, because she feels uncertain about how it will go.

Scenario 4: Dokidoki – again

Another use of dokidoki could be when a character is in danger. The hero, cornered by villains, feels his heart dokidoki as he wonders how he'll escape. It signifies fear and the body's reaction to potential threat.

Thus, while all these words deal with emotional experience, dokidoki is reserved for a more anxious, tense type of excitement, or fear. The difference lies in the nature of the feeling that's producing the heart's palpitations.