Heading into this weekend's penultimate round of the WEC season at Fuji, Hirakawa and his team-mates in the #8 GR010 HYBRID, Sebastien Buemi and Brendon Hartley, lead the drivers' standings on 115 points.
The #7 Toyota crew of Mike Conway, Kamui Kobayashi and Jose Maria Lopez are 23 points down despite their victory last time out at Monza, tied with Ferrari trio James Calado, Alessandro Pier Guidi and Antonio Giovinazzi.
Conway had previously ruled out the #7 car fighting for the championship following its DNF in the Le Mans 24 Hours, but winning at Monza combined with a troubled run to sixth for the #8 drivers has narrowed the difference heading to Fuji.
A maximum of 65 points remain up for grabs across the final two weekends of the season, with the eight-hour Bahrain race offering extra points.
Considering the swing towards the #7 car at Monza and the number of points still available, Hirakawa says he is taking nothing for granted as the title fight approaches its climax.
"We've been fighting for the championship within the team [in previous seasons], so car #7 will be a threat," the Japanese driver told Motorsport.com.
"Car #7 was really strong at Monza, and nobody knows how it will go at Bahrain either. It's too early to say that car #8 is the main hope for Toyota. Both cars are still in the fight for the championship.
"Before the race both cars #7 and #8 will be working together to maximise the performance. And then in the race itself, we fight. It will be a very close fight."
While admitting that he is more confident at Fuji owing to Toyota's strong record of success at its home venue, Hirakawa believes that the marque's Hypercar rivals are not to be underestimated after improved showings at Monza.
"Ferrari should be the main threat, but as we saw at Monza, not only Ferrari, but even Porsche and Peugeot are strong," said Hirakawa.
"They could be fast, and it's not impossible we could end up fighting for P5 or P6. It's not going to be easy.
"But our #8 crew did an amazing job last year at Fuji, so if we can do the same again I think we will be very strong. I have confidence, so I'm looking forward to it."
