The title is taken from Tamako's song off the Twinkle Ride CD, and the fic itself is based on this fanart: pandycake dot tumblr dot com slash post/44049970534.
"Annnko!"
The girl grimaced. She loved her sister, but Tamako's relentless excitement could be tiring. "What is it, Tamako?" she reluctantly called in reply.
"Aren't you coming to help pound the mochi?" Tamako asked, a pleading whine coming into her voice. She appeared around the corner, her face glowing with excitement. "It's Mochi Day, you know!"
Anko smiled at the younger girl. Few of the people she knew had such obvious attachments to their respective family businesses. She'd recognized their neighbor Mochizou's rush on Tamako, but she doubted that it could ever live up to Tamako's love for mochi. "Yeah," she murmured. "But let me finish this."
"Papa said I could make some sakuramochi if we finished before noon!" Tamako chattered happily. "It's my favorite day of the year, you know."
"Yes, I know," Anko replied, smiling indulgently. Truth be told, she mostly wanted Tamako to leave her alone. She needed to stack the boxes of dessert mochi that Tamako had finally convinced their father to make, and she found herself constantly distracted by thoughts of how she could avoid Yuzuki if he came by. If Tamako continued to distract her even further, it would take an hour to stack them all.
But of course, Tamako wasn't about to leave her alone. "What's your favorite mochi, Anko-chan?" Tamako asked, surprised to suddenly realize that she didn't know such a basic fact about her own sister.
Anko frowned as she pushed another box into place. Must Tamako be so obsessed with mochi? she wondered frustratedly. Of course she liked mochi herself, but the extent of Tamako's love for it seemed bizarre. Though it does make her even more special, the voice in her head admitted. "The... chestnut mochi," she said carelessly, not wanting to tell Tamako that in truth, she didn't really have one favorite mochi.
"Oh! Chestnut mochi is delicious!" Tamako exclaimed, apparently not remembering that she thought all varieties of her favorite food were delicious. "But we can only make it for a few weeks each year. That's sad, isn't it? It must be frustrating to be able to have your favorite mochi only once a year."
Anko murmured wordlessly. Whether she agreed or disagreed, she thought, voicing any opinion on the matter would only keep Tamako wound up. "Why don't you go to Grandfather and start pounding?" she suggested firmly. "I'll join you in a little bit."
"Okay!" Tamako said cheerfully, apparently unhurt by Anko's indifference. She bounced out of the room, leaving Anko to reflect that at least her sister's mood was still somewhat pliable. At least when mochi was involved.