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Kathryn Bernardo and Daniel Padilla's "The Hows of Us" has earned another P39 million on its sixth day, taking its box office total to P318 million, it was announced on "It's Showtime" this Tuesday.

Among the KathNiel movies it's the fastest to have crossed the P300-million mark. Their previous effort, last year's "Can’t Help Falling In Love," took three weeks to do the same.

If it can earn a couple of million more, it will become the love team's most successful movie to date, topping not only "Can't Help Falling In Love," but also "Barcelona: A Love Untold" and "Crazy Beautiful You" -- all of which were already considered massive box office successes.

There are plenty of signs signalling a strong run past its first week. Positive reviews from fans and critics, and the long lines in malls have translated to cinema owners scrambling to add more screenings.

The movie initially opened in just 200 cinemas -- a number that has since ballooned to over 400 within just a week. Over Saturday and Sunday, its total went from P117 million to P279 million.

"The Hows of Us" was well-supported by Star Cinema, and its promotional campaign included a surprise admission by its lead stars that they have been a couple for more than five years.

• WATCH: Kathryn recalls first kiss with Daniel

It was also billed as possibly the last movie to team up Bernardo and Padilla with their beloved director Cathy Garcia-Molina, who has expressed her plans to retire and focus on her family.