No. She doesn’t harbor any secret romantic feelings for his dear friend Senku yet. Kohaku holds deep affection for Senku but in a very platonic way. As of the moment, the relationship between the two is only limited to friendship. Although many moments have shown that the two undoubtedly have a strong chemistry. A leap from best friends to lovers hasn’t happened between the two even if they already did something that only lovers usually do.
It is not unusual for main characters like Kohaku and Senku to be shipped by fans. Instead, it is quite understandable, especially in Kohaku’s case, because she is truly Senku’s closest female friend aside from Yuzuriha. Despite her Amazonian characteristics, she is still a woman from within and is a very kind one.

In addition, Kohaku and Senku easily formed a trusting bond from the moment they met. She may not want to admit it. But, Kohaku seeing Senku’s sincerity made her let down her guard just after spending the night together. She is the first person who believed in him and the power of science from the primitive world. Hence, if Senku does ever fall in love, Kohaku will probably be the top candidate for she has been there for him ever since the beginning of the story.
How Did Kohaku and Senku Met?
If it’s meant to be, it will be. Kohaku and Senku’s encounter was more of a destiny than a coincidence. Senku met Kohaku when he needed an ally to beat Tsukasa while Kohaku met him when she needed help for her sister, Ruri. Senku unexpectedly expected met Kohaku right after her fight with Tsukasa.

Kohaku never missed a day in fetching fresh hot spring water for her sick sister. This led to her witnessing what happened between Tsukasa, Yuzuriha, and Senku in the mountains. Kohaku saw how Tsukasa held Yuzuriha captive and how he hit Senku’s neck with the intention to kill him. Therefore, she was determined to fight Tsukasa and avenge the helpless Yuzuriha and Senku whom she assumed was dead when they met. However, Tsukasa’s strength was superior to hers. Hence, she ended up being stuck under a tree which Tsukasa cut down.
Before even falling into any more danger, Senku was just in time to save Kohaku by using the power of science. Right after being saved, she expresses that she has taken quite a liking to Senku. Love at first sight? Not exactly. More like admiration at first sight. Kohaku, later on, explains that this comment was meant to be taken only in a platonic manner.
We just met and she’s already in love? In this state of emergency?
Senku Ishigami to Kohaku (Season 1: Episode 7)
Kohaku was the person from the Ishigami Village who first believe in Senku’s intellect as a scientist and the first one who lend him a hand. Because of her offer to help him, she invited Senku to her village in order for him to gain more allies to fulfill his plans. Therefore, if not for her, Senku would have not met Chrome, Kaseki, and all the people who now are part of The Kingdom of Science.
How Important Is Senku to Kohaku?
I would say very important. Senku holds a very special place in Kohaku’s life, and vice versa. Because Senku lacks the physical ability to fight for himself, she has been both her sword and shield in quite a few instances in the series. She has defended him against the people who mocked and doubted his capabilities and even defended him from his father who completely opposes Senku’s presence in the village.

If we’re talking about intellect then Senku clearly has the top spot. However, when talking about loyalty, Kohaku is definitely tough to beat, particularly her loyalty to Senku. Kohaku was nice enough to invite Senku to her village and was trusting enough to entrust her sister’s life to the scientific innovations of Senku Ishigami. Not only that, curing her sister made her more believe in Senku.
Furthermore, Senku may not be that open in expressing his feelings, unlike his father. However, he cherishes all the people around him, especially those he considered a friend, including Kohaku. Senku acknowledges Kohaku’s contribution to The Kingdom of Science. In fact, he even frequently relies on her brute strength and fighting skills. Her admiration and trust in Senku made her help him and the others without being forced to do so.
Read More: Is Byakuya Senku’s Real Father in Dr. Stone?

Like how best friends are, Senku tends to tease Kohaku because of her immense physical prowess. I mean, both Senku and Chrome usually call her gorilla and lioness because of it. But, it seems like only Chrome gets a beating from Kohaku, not Senku. Instead of receiving a kick or punch, Kohaku just shouts at Senku for his remark and would let him pass it. Is Kohaku playing favoritism? Well, there is a pretty high chance.
Moreover, Senku can easily control the Amazonian side of Kohaku. They have both built a bond that made it possible for each other to influence the actions they will make. Kohaku always worried about Tsukasa finding out that Senku is still alive.

In episode ten of season one, Gen went back to Tsukasa by sneaking out from The Kingdom of Science. This made everyone suspicious of him except for Senku. Thus, to avoid him exploiting Senku to Tsukasa, Kohaku tried to catch him but immediately backed out when Senku stop her. This did not only happen once but a few times throughout the series.
Senku can easily stop Kohaku from making reckless actions that would possibly endanger her life as well. This shows how far their relationship has come and how stronger it possibly will become. This is because it is not only Kohaku who treasures their friendship but also the genius scientist, Senku.
Spoiler Warning: This part of the article may contain spoilers from Dr. Stone’s original manga that is yet to be animated. Read at your own risk.
Did Kohaku and Senku Kiss?
Yes, they did. Senku and Kohaku shared their first kiss in the series’ original manga. As stated above, Kohaku has admitted long before the affection that she has for him right after they met. However, what keeps the SenHaku ship from sailing is that it seems like these two are not yet ready to be romantically involved not just with each other but with anyone.

In episode eight of season one, when Senku needed more manpower for the Kingdom of Science. He assigned Suika to play a detective and learn about the things that the villagers want. Senku hoped to grant them as long as it can be possible through science in exchange for them joining the team.
The three most beautiful ladies in the village, Garnet, Sapphire, and Ruby, shared while conversing with each other that what they want is a boyfriend. While they were on the topic of capable and handsome boyfriends, Kohaku admitted that if it was her then Senku would totally fit in her standard as an attractive man.
Read More: Is Chrome Smarter Than Senku in Dr. Stone?
Furthermore, in the original manga, Kohaku has expressed to one of their allies the standard he looks for in a man. And I tell you, her standard in men certainly fits the unique characteristics of Senku Ishigami. Therefore, developing a romantic relationship is not a punch to the moon as she can easily learn to love him just based on her standards. Love is not that impossible to blossom between them; however, Senku is only fascinated with science even after their kiss.
Someone who follows their ideals, step by step, and hammers away at their goals, no matter how long it takes.
Kohaku describing her ideal man
Senku and Kohaku kissed in chapter 107 of the manga but not because they wanted to do it. Their kiss happened to save their lives and distract their enemies. To not get the enemies from Treasure Island to be more suspicious of them, Gen explained to an enemy that Senku and Kohaku are simply local villagers of the island who were on a date. And to make their excuse more effective, Gen initiated that the two should kiss which Kohaku did without second thoughts. I mean, their lives were in danger. It was a now-or-never situation.

Senku was surprised and was caught off guard by what Kohaku did while she on the other hand was completely unfazed by the kiss. It seems like love for these two characters is not yet something they prioritize. Senku is too focused on rebuilding human civilization and Kohaku is also too busy helping him do that.
But, it is not too late for these two because a possible romance between them has been teased right from the beginning. From Kohaku expressing her admiration when they first met to her kissing Senku. Well, that’s tough to beat if ever Senku will have a love interest in the series. So, for all the SenHaku fans out there, no worries because you guys are on the lead!
Read More: Characters With the Highest and Lowest IQ in Dr. Stone, Ranked