Otsu endured a mostly difficult second season in Japan's top single-seater category with Dandelion Racing, having made the move from Team Mugen after earning Rookie of the Year honours in 2021.
Second place in the final race of the year at Suzuka left him ninth in the final standings, but that result wasn't enough to save his seat, with Honda instead promoting Super Formula Lights runner-up Kakunoshin Ota to partner Tadasuke Makino at Dandelion in 2023.
Otsu will remain on the Honda roster in SUPER GT, stepping up to join Nirei Fukuzumi in ARTA's #16 car after three seasons with Nakajima Racing and switching from Dunlop to Bridgestone tyres.
While grateful for the chance to be part of the Mugen-run ARTA squad in SUPER GT, Otsu made clear his determination to prove to Honda he deserves to be reconsidered for Super Formula in the future.
He added that he wants to use his 2023 season with ARTA to foster a more "aggressive" image.
"It had been decided early on that I wouldn't have a seat [in Super Formula]," Otsu told Motorsport.com's Japanese edition. "Honda has given me a chance to fight in a structure capable of winning in SUPER GT, but I really want to race in both categories, including Super Formula.
"To that end, I want to show everyone a fast and strong version of myself, do whatever is needed to get strong results and make it a season that can lead to further opportunities. I think I feel this much more than others.
"I think people have an image of me being shy and quiet, but I want to dispel that. I want to make it a season where I show my aggression. I think that is something that I have hidden within myself."
Despite losing his drive at Dandelion, Otsu was part of the team's line-up for the post-season rookie test at Suzuka alongside Ota, driving the team's #5 machine in place of an absent Makino.
The two drivers ended up on virtually identical laptimes on the second day of the test, with rookie Ota edging out Otsu by a mere 0.028 seconds.
"It was decided at the last minute that I would participate in the test instead of Makino," explained Otsu. "I was able to discover the characteristics of the #5 car and try some things I wanted to.
"I thought I could achieve a better time, and it's frustrating that I ended up with almost the same time as the #6 car [Ota]. I couldn't do a clean attack lap, but it was frustrating that I couldn't show my performance in the results."
Author's view: Was Honda right to drop Otsu?
On the one hand, it's hard not to sympathise with Otsu. Ninth in the standings puts him above four other Honda drivers in this year's points table, not least of all three-time champion Naoki Yamamoto.
Equally, he hasn't been left without a seat as a result of rejecting an offer like Toshiki Oyu. If the opportunity had existed to stay at Dandelion, or perhaps join his old SUPER GT team Nakajima Racing, he would have surely taken it.
However, when you look at the drivers that have taken those seats - the aforementioned Kakunoshin Ota at Dandelion and Ren Sato at Nakajima - it's clear to see Honda is not only taking current performance into account, but future potential. And that, frankly, is the correct approach.
He may only have two seasons of experience under his belt, but Otsu is already 28 years old, five years the senior of Ota and seven years older than his successor as Rookie of the Year, Sato.
It's probably fair to say that he is already somewhere near the peak of his powers, while both Ota and Sato have plenty of room to grow.
And, his excellent run to second in the very last race of the year aside, Otsu did not really make a convincing case for his retention at Dandelion, lacking the consistency to allow the team to finish higher than fourth in the teams' standings (its worst position since 2018).
The truth is that Otsu, who was passed over in favour of Oyu for Alex Palou's Nakajima Racing seat in 2020, was a slightly odd choice for Mugen's second seat in 2021 to start with. And while he made the most of that opportunity, his move to Dandelion's #6 car felt like a sink-or-swim scenario.
Given Otsu's performances this year, it would have left a more sour taste in the mouth had Sato been jettisoned after an inconsistent rookie season in which he demonstrated some real speed, or had Iori Kimura been given the boot as a result of Ota staying in Lights another year.
And the silver lining for Otsu is that he now has the chance to prove himself in a race-winning package in SUPER GT for the first time.
Certainly, Otsu would make a fine reserve driver for any of the teams in the Honda Super Formula stable for 2023. And, as was the case with Ukyo Sasahara this year, that could lead to a fresh opportunity for '24.
