Your probably right and yes this manga felt more like cancelled as oppose to end. I mean Hajime No Ippo is been going on since 1989 and its a manga with next no fan service.
But yeah its annoying to see loose ends like:
Jise Ro not receiving his backstory
Lack of Kushinadas backstory and what made her to go from katsujinken to a mass murderer
Ogatas timeline with Ryozanpaku master and if he had any other martial arts masters/experience before Ryo
Gannosukes lack of disciple since OSNF/Hachiou are all known for disciples. Otherwise Sai Kagerou would have qualified if these groups were based on how strong masters are.
Sakakis master, it was implied that he was a very very ruthless satsujinken since Sakakis karate style is known for brutality. Also would like to know Sakakis "kill" move
I personaly was not the biggest Jenazad fan but I always wondered what would Jenazads "Ultimate Silat" technique would look like? I mean the only two people that have shown us "Final" moves were Kushinada and Shigure. Both moves seemed like they lack defense and were mostly made for relentless offense.
We saw a number of ultimate moves, actually:
Apachai & Agaard's: Bolisud Look Mai, a brute strength outburst that achieves similar effect to when Saiga and Senzui clashes, destroying several floors in a huge blast.
Shigure: a move where she appears to manipulate the ki of all weapon users nearby, forcing them to attack shadows and allowing her to fight multiple opponents of equivalent levels simultaneously.
Kushinada: a move where she appears to manipulate the ki of all master class fighters nearby, making it appear like they are fighting clones of her.
Hongo: a straight forward thrust using Hongo's entire upper and lower body strength couple with spinning. This is Hongo's "beyond ultimate" move, where he literally went added his leg to his already ultimate move. Just the air blast from this move is enough to cause a big clean hole through masonry as if the wall was hit by a tank shell. But if the move misses, then he's wide open and lost balance... well, let's hope the organ lift trick works again.
Alexander: forward march of death. Gaidar drops all defenses and go in with the intention to take his opponent to hell with him. Achieves much of the same effect as Bolisud Look Mai.
Elder: that move where he dropped like a comet into the forest, causing a HUGE crater and an explosion that looks like a MOAB (the largest conventional bomb)