And I swore I’d never let her eat plain rice alone again.

I already knew. The electric bill was due. Her part-time job at the bookstore had cut her hours. And she’d spent her last yen on a get-well card for a classmate’s mother.

Here’s a short text based on your prompt:

My imouto's financial struggles have started to affect our family in several ways:

She stared at it. Then her eyes glossed over—not with sadness, but that stubborn, angry love of someone who hates needing help.

If you're looking for a more direct way to help financially, consider:

In most slice-of-life series, the imouto’s financial woes usually stem from one of three distinct "money pits":

Every cent goes toward limited-edition figurines, gacha games, or voice actor CDs.