Sweet Lesson

An unofficial, fan-made doujin based on the popular shounen manga and anime series, "Katekyoushi Hitman Reborn!". Sweet Lesson is based upon the events of the original series, ending sometime during the Future Arc. Replacing Sawada "Tsuna" Tsunayoshi as the main protagonist is Sawada Tsunako, a female version of Tsuna. Despite the gender change, Tsunako is practically no different from Tsuna. 

Though being called "Dame-Tsunako" (No-good Tsunako) by those around her, Sawada Tsunako's (default name, changeable) life in the township of Namimori has been peaceful.

However, Tsunako's peaceful days came to an end when her family appointed her a home tutor named Reborn, whom despite being a baby, is a highly successful Hitman. However, that is not all- Reborn also revealed to Tsunako that she is directly in line to become the 10th generation of Italy's most powerful mafia organisation, the Vongola Family. Forced into accpeting his training and lessons, Tsunako reluctantly complies.

After undertaking many of his teachings, Reborn one day introduces Tsunako to her latest lesson:

"A-again, Reborn, with the outrageous lessons!"
"What was that 8th boss-person thinking when she made up THAT rule?!"

"It's a total bother!"

In order for Tsunako to be eligible to become the 10th boss, she has to follow a rule that Daniella, the only female boss in the history of the Vongola Family, has left behind...

...And that rule is..?

Sweet Holic's blog entry (which is a re-print of the official website's blurb).