Early one morning, Usagi woke up to a strange sensation. It was a wet spot on her bed, right next to her dear little Chibiusa.

"Chibiusa!" Usagi exclaimed, waking the little girl up. Chibiusa looked around, realizing what had happened and immediately started to cry.

Usagi quickly comforted her, hugging her tightly. "It's okay, Chibiusa. Accidents happen. But we need to wear our diapers to bed, okay?"

Chibiusa sniffled, feeling embarrassed. "But I don't like them... They're uncomfortable," she admitted. Usagi nodded, understanding her feelings.

"I know, sweetheart," Usagi said gently. "But it's better than waking up wet, isn't it?" Chibiusa nodded, still looking a bit upset.

"Let's get you cleaned up," Usagi suggested, leading Chibiusa to the bathroom for a warm bath. Chibiusa seemed to cheer up a bit at the idea.

As Usagi gently bathed Chibiusa, she decided to share a little secret. "You know, when I was your age, I used to wet the bed too."

Chibiusa looked up at her in surprise. "Really?" Usagi nodded, smiling gently. "Yes, and I had to wear diapers to bed too."

"But you're a big girl now," Chibiusa said, looking at Usagi with admiration. "Yes, and one day, you'll be a big girl too," Usagi reassured her.

Usagi then made a little promise to Chibiusa. "If you can stay dry for a week, I'll buy you a new toy. How does that sound?"

Chibiusa's eyes lit up at the thought. "Really? Any toy I want?" Usagi nodded, chuckling at her excitement. "Any toy you want."

"Okay! I'll do it!" Chibiusa declared, looking determined. Usagi smiled, proud of her little girl's resolve. "That's my girl."

The days passed and Chibiusa worked hard to keep her promise. She wore her diapers to bed, drank less water before sleep, and even set alarms to use the bathroom.

Usagi was there every step of the way, encouraging her, helping her, and reminding her of the promise. They were in this together.

Chibiusa had a few accidents, but she didn't let it discourage her. She kept trying, each dry night bringing her one step closer to her new toy.

Finally, after a week, Chibiusa woke up to a dry bed. She was overjoyed, and so was Usagi. They had done it.

"I'm so proud of you, Chibiusa!" Usagi exclaimed, hugging the little girl tightly. Chibiusa beamed, proud of her accomplishment.

That day, Usagi took Chibiusa to the toy store. The little girl's eyes widened in awe as she looked at all the different toys.

After much deliberation, Chibiusa chose a plush bunny, hugging it tightly. Usagi smiled, happy to see her so happy.

"Thank you, Usagi," Chibiusa said, looking up at her with gratitude. Usagi hugged her, saying, "No, thank you for working so hard, Chibiusa."

That night, Chibiusa slept with her new plush bunny, feeling content. She had learned an important lesson and gained a new friend.

Usagi watched her sleep, feeling proud. She knew Chibiusa was growing up, and she was there to guide her along the way.

The promise of dry nights had been kept, and a new chapter in their lives had begun. Through love and understanding, they had overcome a small challenge.

And so, as Chibiusa continued to grow, Usagi was there to support her. Just as she had promised, she was there for every step of the way.

For Usagi and Chibiusa, each day was filled with love, learning, and growing. And through it all, they knew they could always rely on each other.