Adorkable: Being a Jerkass or not, Hayato proves he's clearly an adorkable person, usually by awkwarding himself or everyone out. This is especially noticeably around Seto.
Badass: Like all members of the Club, Hayato is a definite Badass.
Badass Bookworm: He's the most perceptive and smartest around his friends and even manages to outranking Crystal's in school.
Took A Level In Badass: Hayato becomes the Badass he is after the continous time loops he and Mary went through.
Beneath the Mask: As the Kagerou Daze arc shows, Hayato is clearly not the person we all thought he is...
Berserk Button: Hayato really doesn't like to remember the timeloops he went through, as proven by poor poor Mary. And even then on, he really dislike Mary THAT much.
Beware the Nice Ones: Really....
Big Brother Instinct: Towards Zadkiel/Hotaru, which he shows much more sugar side of him.
Break the Cutie: In Mary's Haze arc. The effects of Mary's timeloops and Kuroha's Mind Rape doesn't make it any better for Hayato's state of mind at that time.
Broken Bird: Courtesy of being the only member of the Club to survived all the timeloops and then repeatedly remember all of them just because Mary resets it. Let's just say, that Hayato is completely broken at that point.
Childhood Friends: With Amethyst.
Cool Sword: Mnemosyne
Combat Pragmatist: Shown to be an effective one. Considering how he manages to fool Beat and Rhytmi by thinking that he's dead while taking them on surprisingly.
Healing Hands: Due to being a Spirit Slayer, his healing spell is much more effective than the Sky Dragon Slayer's.
Making A Splash: His Spirit Slayer magic.
Wave Motion Gun
Cry Cute: In Mary's Haze arc.
Cynicism Catalyst: Hayato becomes the cold person he is due to having enough of Mary's resetting.
Dangerously Genre Savvy: Due to experiencing the time loops, Hayato is definitely aware of what's going to happen and manages to be incredible dangerous when he's serious. As shown during his fight against Beatrice in Next Generation and against both Rhytmi and Beat in Revenant Night.
Dark And Troubled Past: Like all of the Club Members, Hayato experienced a Near-Death Experience that activates his Water Seal. And let's not get into the timey-wimey thing he has with Mary...
Defrosting Ice King: After Mary's Haze arc, Hayato noticeably mellows down a bit and is much more appreciative towards both Mary and Seto (although the latter still irritates him to no end) and his interactions with Zadkiel/Hotaru is the one thing that thaws him out.
Despair Event Horizon: After relieving too many time loops caused by Mary and seeing his friends die in front of him many times, Hayato really loses his optimism in the current timeline and puts up a facade to hide his true feelings.
Hayato's not-so-sarcastic remarks towards Amethyst and Teito, hits Amethyst when she's being stupid, and acts weird whenever he's around Kakeru. This all fits in pieces into revealing Hayato's feelings behind his "nice guy" mask.
Also, him knowing Seto and Mary's name despite he should not have met them before foreshadowing that Hayato remembers the time loops Mary creates.
Forgotten First Meeting: He first met Seto when he saw him taking care of a stray Lillipup. The same Lillipup that Hayato has one, now a Stoutland. Although, both of them never remembered this until Keith accidentally saw the memory when he's about to purify Seto's Dark Haze.
Get A Hold of Youself, Man!: To Mary in Mary's Haze arc and Seto in Dark Haze arc.
Good Is Not Nice
Good Is Not Soft
Groundhog Peggy Sue: Along with Mary, Hayato continously enters the many time loops that Mary has reset and had to watch all of his friends died one by one.
It's All My Fault: Blames himself for not trying to save the Club from getting killed by Kuroha in the first time loop.
Jerk With A Heart of Gold: What Hayato turns out to be. Although he's less of a Jerkass when it comes to other members of the Club except Amethyst and Zadkiel/Hotaru.
Jerkass Has A Point
Jerkass Facade: Both Inverted and Played With.
Laser-Guided Amnesia: Like all of the other Club members, he forgot that he nearly died due to the Water Seal inside of him activated.
Morality Pet: Both Seto and Zadkiel/Hotaru are one for him.
My Greatest Failure: All the members of the Club except him and Seto getting killed by Kuroha in the first loop.
Near-Death Experience: He nearly got drowned after saving the Lillipup he was taking care of as a kid and again when he saved Seto's life from being drowned by Kano. Both events are what activates his Akasha Seal.
Nice Guy: What he was, and is whenever he's not being a Jerkass to any of his friends.
Red Oni, Blue Oni: The Blue to Amethyst's and Seto's Red.
Ripple-Effect-Proof-Memory: Due to being the only survivor aside from Mary, Hayato remembers all the events of the time loops caused by Mary. And the results are not good for his sanity...
Seen It All
Survivor Guilt: For not trying to stop Kuroha from possessing Roku in the first loop that caused all the members of the Club and Mekakushi Dan getting killed and the other loops after that.
Spanner In The Works: Thanks to Kuroha not realizing that Hayato survived in the first loop and remembering all the events of all the loops is what allows Hayato to be able to save Mary, due to being immune to all of Kuroha's powers as a result thus made Keith realized to Take A Third Option.
Took A Level In Jerkass: As a result of Mary's resetting. He hides it from the rest with the original personality of his until Kagerou Daze arc when he met Seto.
Trauma Conga Line: Between result E or G.
Tsundere: Type A towards Seto and pretty much everyone else, except Zadkiel/Hotaru.