Izuru is a gloomy and introspective person, not easily given to socializing with others. He generally appears weak and diffident, leading many to believe he lacks ability as a leader. As an officer, he does not tend to inspire confidence or boost morale the way other lieutenants do. However, in combat he shows ruthless determination. Izuru has shown himself remorseless with this, beheading opponents who were pleading for mercy.

His personality flaws are also assets: his introspection coupled with his tendency to worry makes him indecisive, but it also makes him sensitive to unusual behavior. His loyalty to his comrades inspires him to great efforts in their defense, as seen when Momo Hinamori attacks Gin Ichimaru and again in the anime when Makoto Kifune's attacks endanger other members of the 3rd Division.

Izuru is loyal to both his friends and his duties, perhaps to a fault. Despite the close friendship he shares with Momo Hinamori, Izuru shows that his loyalty knows no boundaries when he defends his captain while she is in a grief-induced rage from her own captain's apparent death. Despite this, he calls himself a 'monster' afterwards for raising his sword against her.

During his fight with Avirama Redder, it is revealed that Izuru considers the essence of war to be despair, as exemplified by the symbol of his division, the marigold. He also hates to fight unless prompted or given orders.

It is known that he likes to write haiku, and he was also awarded for one of his pieces by Seireitei Communication, which is as follows:

"The persimmon tree bears fruit. Aaah, the persimmon tree bears fruit again this year."

His dislike for dried persimmon (a huge difference between him and his former captain) sheds some light on the background of the poem. He likes agar-agar instead. He also writes a serial novel titled "I Want to Apologize to You". It runs in Seireitei Communication and every new chapter begins with a haiku piece. He is on good terms with fellow author Sh?hei Hisagi, and in their free time, they participate on gatherings of haiku-lovers. Izuru also gives a special lecture of poetry on the Shinigami Academy. It is also known that he is skilled in playing cat's cradle.