Uchiahmasters
merriam webster dictionary definition of sexism
1 Prejudice or discrimination based on sex especially discrimination against women
2 behavior conditions or attitudes that foster stereotypes of social roles based on sex
definition of a sexist
1 Relating to, involving, or fostering sexist, or attitudes and behaviors toward someone based on the person's gender: a sexist remark
2 a person who has sexist attitudes or behaves in a sexist manner
showing Tsunade's boobs doesn't meet either definition
and as for objectification
a person can only be objectified if there body is being used in a manner to achieve a goal for the author of said manga or anime
ie to sell the story but thats not what happens when ever they show tsunade's boobs its usually to show the viewers that jiraiya is a pervy sage
Objectification is a notion central to feminist theory. It can be roughly defined as the seeing and/or treating a person, usually a woman, as an object.
and requires an objectifier and a purpose for the objectification other than to get a quick laugh or to show a characters perviness example in nanatsu no taizai meliodas is constantly grabbing Elizabeth ass is the anime and manga objectifying her? No because its not designed to meet a goal of the authors its simply a trope designed to show how meliodas is a perv
More over said so-called objectification requires the objectification to overshadow other qualities a character has in this case Tsunade's breasts would have to overshadow her innate power and ability as a Shinobi. it doesn't and therefore its not objectification