We know he's suppose to be charmingly immature but it really started pushing it near the end, especially when he started making moves on her despite the fact that she was currently in a relationship with Mamura and had decided for the SECOND time to move on after heartbreak from rejection with him (also not to mention confusing and hurting our MC several times with his ambiguous responses). That is NOT okay. Especially given that she's beginning to find happiness in her newfound love with this bestie once more. However, I do wish there was more buildup between Mamura and Yosano as much as she had with Sensei.. the plot felt rushed to quickly reach a conclusion. Despite that, at that point I wouldn't have minded if she had ended up even with Inukai or any other guy instead though. If she were my girlfriend my advice to her would be to stay far, far away from this teacher of hers. She is 16 years old and this is a guy who is 8 years her senior doesn't seem to be capable in making a sound and concise decision. irl, her relationship with Sensei would have been passionate but short-lived. If not short-lived, a very thorny and painful path. The idea of her ending up with Sensei was more romantic but choosing Mamura was the most realistically pragmatic decision she could make. He loves her selflessly, her Sensei does not. Mamura thinks of all the ways she can be loved, fulfilled and happy (even at his own expense) but her Sensei does not. Her teacher's later actions were so indecisive and destructive to our heroine's growth and love that it makes one wonder whether he's undeveloped in maturity or underdeveloped as a character. Seriously, it makes it seem that this highschooler boy is more courageous in loving our lead than this man. It doesn't make the love both the teacher and Yosano had any less significant but it's ultimately one-dimensional compared to what she has with Mamura. Quoting her, through Mamura she learns that to love is to give love and happiness to the other and not just focused on one's own emotional fulfillment through the rip-tides of passion. She learns by what he has shown her that throughout the times he's been with her. Now that is the kind of relationship that lasts a lifetime.

LIKE SERIOUSLY HE REJECTS HER AND THEN TRIES TO HUG AND KISS HER. JUST STOP PLAYING WITH MY SHIZUME FEELS

Here we go. For the most part, I'm just talking about the ending and referring to the whole plot (mainly because people are so darn salty about the ending). And may I point out again that I am a Shizume shipper. Also a Mazume shipper but I ship Shishio x Yosano more. I thought the ending was perfect. It was so satisfying and such a good wrap up. What people who don't like the ending have to understand is that the mangaka wasn't trying to make a perfect ending. I don't want to seem like I know her and what her purpose was but it seems strongly to be that she created an ending which supported the plot of the story. Yosano fell in love with her teacher but got rejected. He started to like her too but couldn't tell her. All of this tension was built up until the 47th chapter - the turning point. Before this, I thought they were going to be canon but it was obvious on that chapter that their love was never going to work out. It was heart-wrenching to read. You get flashbacks of all the good times they had and all of it came crashing down. After this, Yosano tries to get over him and realises slowly that Mamura had always been there. I thought the transition was a little too abrupt, it almost made it seem like she went from one guy to the next. The ending finishes with Shishio finally confessing and then Yosano rejecting him. This chapter was astounding. It shows the true development of Yosano over the manga and how strong she had become. Also with Shishio too, he maturely accepts the fact that he lost Yosano as she races back to Okinawa. There, she is truly happy. She chose the path that didn't cause her pain and agony. Mamura and Yosano were the perfect couple. It was the message of the whole manga. So why do I ship Shizume so much? I have a lot of reasons but I won't list them here in the manga review ahaha

The love between Yosano and Mamura was so sudden. Out of nowhere, Yosano tells us that she's fallen in love with Mamura. For Shishio, it was built up over time but again, Yosano seems to fall in love with Shishio much too quickly - you could argue that it was just first signs of love and her understanding of why she loved him grew over time. The pacing of the manga was slightly askew and it makes me wonder is Shishio literally having mood swings or something because he goes from showing Yosano all the love in the world to the silent treatment.

Then it's pretty clear from the beginning that she was going end up with Mamura over Shishio. Just because Shishio was the first love interest, doesn't mean he was the main love interest.

tho sensei is partly at fault here. He could've just asked Suzu to wait until she gets to be an adult or something

Suzume is hurt because it's obviously her first love and she's confused, moreover she understands that they cannot possibly be in a relationship. And Shishio-sensei,well, he fell in love with a child even worse - with his student and he feels pretty bad about it. I think one of the best moments in manga when he looks at her and thinks: we are from different universe. It really speaks well for him: he gets that it's a crush but also understands that it will not lead anywhere. And I must admit he behaves decently, well, yeah, I don't like how he grabbed her sometimes to hug (just a couple of times) or to take someplace to talk but other than that (THANKS GOD) he doesn't do anything improper, they just hold hands couple of times that's all and I cannot express how much I'm happy about it.[
I personally don't advice you to read pass their breakup (oops, SPOILER, but let's be honest it was the only way to handle it) because it ended just perfect and the rest of manga, well... ¯\_(ツ)_/¯ I read it till the very end but honestly the rest of the story is just not good and plain and boring and there is no decent explanation of this deep love Suzume and Mamura sharing in the end - their relationships had no development whatsoever.
Moreover, I liked Mamura at the beginning, I knew it would be a love triange here so I thought: it's a good idea for them to be together, 'cause they are same age, interests, degree of maturity and all, what can go wrong? Well...
EVERYTHING. ≧△≦ Mamura is a d*%"head, really, he's a little abuser and even it implies that he supports Suzume all the time while she's in pain but... no, not really (he hugged her after she got rejected once and he did pretty much nothing after she got her heart broken. Oh, yeah he gave her his scarf pffft) Moreover, he's very rude towards her all the time, even when they become friends he still acts very uncaring and call weak and stupind, even when he confessed to her he called her an idiot＞＜, he hits her forehead (not hard but still it's an abuse) and do it reguraly with no reason, screams at her and ignores her opinion etc. This is nowhere near the romantic love story I expected, even the last page was awful (SPOILER ALERT: when Mamura is going to propose her he thinks smth like "I have to make a lame speach and I will never accept "no" for an answer from you, idiot" - he neglects her real feelings and obviosly he's not very fond of being romantic with her).
Secondly, their love (Mamura and Suzume) stars really strange, first they pretend to be couple, then he confesses (again), then they are a couple for real blah blah and there is a strange twist when at one moment Suzume is talking to her friend about how she felt - that she's confused and she doesn't know if her appreciation of Mamura is as a friendship or romantic feeling and in just in a moment she's rushing towards Mamura's house to ask him out (WTF?!). And again, I can relate to it: she likes his company (althought he's a d*&%) and want to spend more time with him but where all those feels and emotions that we see in the end of manga are came from? Where? They had a couple of dates, he screamed at her in front of the aquarium, then dropped a toy on Suzume's head (soo, soo romantic (not really), they went to a trip on vacation... sooo? Once again why are they so in love? When did she start feeling it? When did she finally recovered from the pain her previous love gave her? (Well, there is this moment in a manga actually but it's not very conviencing) It's like there is A LOT missing in the plot and the ending is just duuuuh - why did mangaka need to make this strange side story about Shishio 6 years later (SPOILER! he meets a girl living next to him and they talk a couple of times and it ends just in the middle of the conversation! If you really wanted to make it clear that he started something new (yeah, just six years later and he has "sad eyes" from that very love story with Suzume. *rolls eyes* it looks even more stupid comparing with how little time Suzume needed to start a new love, oh, i'm sorry A NEW EVERLASTING ROMANTIC TRUE LOVE (=_=) [/spoiler]
Well, anyway... As you see the plot is not bad (it's not good either, it's just usual shoujo manga, you know) and the storylines and love triangles are just fine, and I even think the student-teacher love story wasn't that bad (I still don't approve but at least it was realistic: confusing, uneasy and inappropriate and ended accordingly, and yeah, you still can sympathize with both Suzume and Shishio even if you think that those kind of relationships shouldn't exist). But the second part of the manga is just not worth of your time.

BTW, there are a lot of really forced twists and coincidences (in fact, the whole Suzume-Shishio storyline is a conjuncture): Suzume meets either her teacher or Mamura in huuuuuuuuuuuuuuge Tokyo all the time no matter where she goes: to New Year's Festival or to a temple etc, needless to say they bump into each other in school all the time, it looks fine at first but in the end it becomes really annoying and unnatural and sabotages the whole story.

I don't like how the author handled Suzume's relationship with Mamura.
Their relationship was not given a thought and Suzume just magically falls in love with Mamura without reason while she had a hard time before in distinguishing her feelings for sensei.
I also don't like how they have taken out Sensei out of the picture so Mamura can enter Suzume's field of vision.

What's also the deal with the uncle, it not like sensei is commiting a crime and sleeping with her. What so bad in courting or showing your feelings to your student. I think sensei is willing to make a compromise and wait for her to graduate before truly making a bold move on her but then the uncle just have to over react.

I'm still mad about this.
I'm not against Mamura but I didn't like the ending at all. It was force...
I truly believe that sensei is Suzume's daytime shooting star...