Looking for novels with interesting and unique master student relationships. The master of the mc isn't just some wise and powerful figure, but a well written character in their own right and how they interact with the mc their student isn't cliche in how they get along. The relationship also doesn't have to be kind or healthy. They can even hate each other, or the master is teaching the mc because he is a talent is is worth investing in for their own self interest later on. Anything outside the norm is appreciated. Also the master in question doesn't have to be a god tier or world class individual. Edit. I wasn't looking for romantic relationships when I used the word "relationships".
I have read breakthrough with the forbidden master until chapter 300 in japanese. Its a really good shonen with nice chara development and a deep master-student relationship.
Ascending, Do Not Disturb. It's a finished novel on novelupdates. 158 chapters, well written and translated. World building is impeccable, ALL characters have depth (not to the extent of filler). Comedy, slow romance, female protagonist, MC has a slow heartwarming romance with a powerful sword cultivator (he is on a journey to collect ingredients for his medicine). MC has a master, it's a healthy master-disciple relationship. The sect MC joined is a nest of momma bears, don't mess with any of the disciples because the elders will come out to protect and revenge. My Disciple Died Yet Again. I have read the webtoon (Manhua), this novel is on my list to read. It's a finished novel on novelupdates, 393 chapters. Female protagonist, a game developer that transmigrated from the modern era to a xianxia VR game that is currently in development. She was picked up by her master, and dies and reincarnates a bunch. MC throws away her life to protect others too much, her master waits for her to reincarnate to pick up his disciple again. She retains all her memories each time, and the period of time she takes to reincarnate is about 50-100 years (if I'm recalling this correctly). And she doesn't always reincarnate as a human. There is a somewhat noticeable romance between MC and her master. I enjoy wuxia/xianxia cultivation novels, but I don't read many Master-disciple focused novels.
Somehow Reverend Insanity comes to mind, when the MC interacts with others, he often in a 'teacher' relationship since he has a lot of knowledge. Not sure if that's entirely what you're looking for though.
I'm not sure whether or not History’s Number 1 Founder counts, since MC is the master in that case. I'd recommend Super Dimensional Wizard/Warlock Apprentice as well, but be warned that it's really, really slow, really long and also has a lot of infodumps. Oh, and it's dropped. The master-disciple relationship is not one of the biggest features, although the mentor is the second-most often appearing character, after the MC.
Once Upon A Time, There Was A Spirit Sword Mountain has the shameless duo of the scheming Wang Lu and his master, the Number One Jindan (Golden Core) Under the Heavens, Wang Wu. There is actually a deep connection between the two, but you are more likely to find them playing pranks on each other on a random day. However, whenever they interact with other people, strange shenanigans occur, to the point other people don't know whether to laugh or cry (but you will laugh. A lot. ). The manhua of the I Have Refined Qi For 3000 Years! is also very good. Specially once certain someone becomes the disciple of the main protagonist. And much more, once shenanigans occur & the main protagonist ends up at certain VERY STRANGE PLACE where he finds his second disciple. And a goddess. P.D. Beware of Chicken (Royalroad) sort of counts, I guess? The protagonist doesn't formally become a master, but everyone starts treating him as such (or at the very least, like the Patriarch of the family).
My Master Disconnected Yet Again A novel with a summary similar to Ascending, Do Not Disturb recommended by @koco2018 but I don't know about the rest because the only parts similar were slow romance, comedy, ML being a powerful sword cultivator, female protagonist, a master-disciple relationship. The FL is not very proactive as the ML in their relationship, not because she doesn't like him but she does not know how to express herself. Altogether she is cute (exclude the fact that she is OP). Definitely a great one if you are ok with a romantic relationship. https://www.novelupdates.com/series/my-master-disconnected-yet-again/