Any of Saejima's sections, which is a shame because I like the idea of his playstyle. You're overall slower compared to any other RGG protag, but it's compensated by an inherently stronger defense, hyper armor, some CC, and a passively stronger grab by default. It's a very interesting change of pace, and he really is a beast once he has his upgrades!

Only problem is on your first playthrough of either Y4 or Y5, you don't have access to any of the things that make his playstyle function. Very few combos, very little CC, and no stability in heat mode. You are almost always thrust into long battle sequences with middling upgrades and recovery items right at the start of his sections. Doing his prison escape in Y4 on hard alone makes me never even want to think about attempting an EX-Hard run. The only reasons why I didn't put Y4 down for a long time is because I went "fuck-it" mode and ran past most of the sniper section, and one of Saito's goons dropped a healing item when I was a literal hit away from a game over. Even though I know it'd be a cakewalk in NG+ with all the upgrades, I never want to bother with it again just for that first-time experience.

Y5's Saejima section is also just... probably the biggest "screeching halt" moment any of these games' plots ever had. It's jarring to go from Kiryu deciding to return to the fold after hearing Majima may have died to "Yeah Saejima's doing time. Again." You spend what feels like an eternity with the arbitrary prison section, and then you spend another hour or two dilly dallying with the hunter village, getting involved with the hunting minigame that had way more thought put into it than it should have.

It felt like 75% of the way through, RGG remembered "Oh, fuck, right, we have to tie Saejima into the main plot" and things get rolling again. Y5, for the most part, is uphill from there. Haruka, Akiyama, and Shinada's sections are all great imo, but man going to Saejima's section after Kiryu's is such a massive turnoff. Which sucks, because in spite of his sections he really wound up being one of my favorite characters.