Tasuki has lost a lot of people close to him in the past and the present. Each loss has had an emotional impact on him since each person was considered dear. I decided to elaborate a bit on each individual and focus on what type of relationship they had with Tasuki.'
This section contains major spoilers. Do not proceed if you haven't seen or read the entire series. Otherwise, proceed at your own discretion.


Hakurou

Tasuki's mentor, the man he had such admiration for after their first encounter at Mt. Leikaku. He wanted to be just like him, to follow in his every footstep. Meeting Hakurou was a turning pointing in Tasuki's life once being initiated under his leadership as a member of the Mt. Leikaku bandits. However, about two years later, while Hakurou was preparing his two best bandits (Tasuki and Koji) to succeed him as leader, he was overcome by a terrible illness. One, which claimed his life as he laid in bed after finally granting Tasuki with the honorable title of leader. It was a huge loss for the warrior seeing that, in my opinion, he was the first person he looked up to and had utmost respect for. If you want to learn more about Hakurou, you should read Fushigi Yuugi Genrou-den. It's basically a prelude on Tasuki.


Reirei

Reirei is the fourteen year old girl who fell in love with Tasuki. She is the sister of the leader Keiron, of the Mt. Kaou bandits. She died honorably trying to retrieve and protect the treasured Tessen which was stolen from Mt. Leikaku. In a desperate attempt to present the Tessen back to Tasuki and prevent it from landing in the clutches of an evil youkai, she plunged from the top floor of Souun Castle to the garden below. Tasuki was distraught and in tears when he discovered her soon to be lifeless body. It was the first huge loss for the Suzaku warrior.


Nuriko

The death of this Suzaku warrior is deeply embedded in my mind. Tears threatened to explode from my eyes as I watched his life fade away. I know. I know, it's just animation but I'm not ashamed to admit it. Tasuki seemed the most distressed about it besides Miaka. I think Nuriko was the warrior Tasuki was closest to apart from Chichiri. In addition, the Suzaku Seishi is the closest family Tasuki has aside from the Mt. Leikaku bandits, closer to him than his parents and siblings. He and Nuriko conversed a lot and they seemed to add the most comic relief throughout the series.
(I'm not going to elaborate on how he died. His death alone is a huge spoiler.)


Mitsukake

The two weren't really that close but they had a good relationship with one another. Mitsukake was very quiet so it may seem like he hardly had a relationship with any of them. Tasuki was with Miaka when he first met Mitsukake, who was dealing with the loss of his fiancé Shoka. They were there with him when he finally released his regret and guilt over her death. When Konan and Kutou finally went to war, Mitsukake died giving aid to the many villagers and warriors who were injured while on the battlefield. It was another emotional loss.


Chiriko

Chiriko didn't really have a large role in the series except for the fact that he was a warrior of Suzaku. However, the few times he made his appearance were very commendable. Even though he's very young, he was still very courageous in everything he did till the very end. He selflessly and bravely gave his life to protect the priestess while they were under attack by one of the Seiryu Seven. Such a selfless feat arose deep admiration from all of his fellow comrades including Tasuki. (He cried like a baby)


Hotohori

These two never had much contact with each other. They weren't very close and hardly ever conversed. But, like every other Suzaku warrior, they considered each other as equals and had high regard and respect. All the warriors treated each other like family.
That's why his death has just as much impact as all the others. Hotohori died bravely and honorably in the war defending the Conan Empire.


Tamahome

Tamahome, one of the main characters of the series, had a great relationship with Tasuki. Their friendship commenced at a rocky start but as the series progressed, they became “humor” buddies. I quote “humor” buddies because in majority, when together, they added a bit of comic relief throughout the series.
Tamahome was the last of the Suzaku Seven to encounter death, his life withering mercilessly at the hands of Nakago. It devastated Miaka and it affected Tasuki tremendously as well. He died honorably trying to protect Miaka and her world to the bitter end.